XBRL-enabled software may have features to simplify working with tables, but this portion of the guide provides preparers with enough detail to understand tables regardless of the specific software.

As discussed in Section 3, Understanding and Using Taxonomies, tables provide a way to capture multidimensional relationships among elements. Multidimensional information is often presented as a table. Figure 35 is an example of a table with two axes: the Available-for-Sale securities line items axis and the type of Available‑for‑Sale security axis.

Figure 35 XYZ Company and Subsidiaries, Available-for-Sale Securities Reconciliation of Fair Value (Original Preparer Layout)

Within the line items axis, there are four line items (cost, gross unrealized gains, gross unrealized losses, and estimated fair value). Within the axis of type of Available-for-Sale security, there are three members of a domain, representing three types of securities (US Treasury Notes, Corporate Debt Securities, and Equity Securities), and the total for the three members of the domain. The XBRL US GAAP Taxonomy distinguishes between the line items axis, which has financial reporting elements (much as they appear anywhere in the taxonomy), and the domain members, which are types or subcategories of items described by the financial reporting elements. Tables can also include aggregated amounts for their line items (the total column in Figure 35). Figure 36 presents an illustration of these terms (axis, domain, and member) and what they represent within a table.

Figure 36 Elements of a Table

As Figure 36 shows, the following elements are used to define an XBRL table:

• Table: A table element represents the overall "table" and is the parent element for axes. A helpful way to think of the concept of a table is to picture a blank spreadsheet with empty cells.
• Axis: A table can have any number of axes. Each axis must have at least one domain.
• Line Items: Line items are elements that appear on the vertical axis of an XBRL table. Every table must have exactly one abstract element ending with "[Line Items]".
• Domain: A domain is the set of all domain members appearing along an axis and also represents the total of values of all domain members.

• Domain Members: A domain member is an element that appears on an axis other than the vertical axis of an XBRL table. In a two-dimensional table, domain members represent elements on the horizontal axis.

Figure 37 overlays the appropriate table element on each part of the table from Figure 35.

Figure 37 XYZ Company and Subsidiaries, Available-for-Sale Securities Reconciliation of Fair Value (Published Financial Statement View with Table Overlay)

Figure 37 represents a table with two axes. Each axis also has a domain (only the type domain is labeled). The domain members (conventionally, the horizontal axis) include US Treasury Notes, Corporate Debt Securities, and Equity Securities. The Total is not a separate domain member; it is represented by the domain element. The line items (conventionally, the vertical axis) include Cost, Gross Unrealized Gains, Gross Unrealized Losses, and Estimated Fair Value.

5.1    Table Elements and Relationships

XBRL tables are defined using dimensional relationships and must adhere to the structure shown in Figure 38. The XBRL US GAAP Taxonomy also has table elements that appear in slightly different presentation relationships, but this is to facilitate browsing and review; only the dimension relationships matter to XBRL-enabled software.

Figure 38 Parent-Child Table Structure in Dimensional Relationships

The following material presents an explanation of each of the elements in Figure 38.

5.1.1 Line Items Abstract Element

In the XBRL US GAAP Taxonomy each table has exactly one abstract element whose standard label ends with "[Line Items]". The children of the Line Items element are the table element and all the line items: the monetary, string, decimal, and other types of elements that appear along the vertical axis.

5.1.2 Table Element

The XBRL table is an abstract element, and the axis, domain, and member elements must be subordinate to it (that is, child, grandchild, great grandchild, and so forth). A table is used only if preparers need to represent information that is characterized in two or more axes.

5.1.3 Axes Are Children of Table Elements

Axes are abstract elements that are children of table elements and represent the different ways in which data can be classified (for example, actual [as opposed to plan or forecast], type of security, or class of fixed asset). A table can have an unlimited number of axes, but the more axes it has, the more difficult it will be to work with for preparers and other users of the extension. Regardless of how many axes a table has, the rules for their operation are the same. For clarity, this guide generally limits discussion to the horizontal axis and the vertical axis.

An axis cannot be the child of more than one table.

5.1.4 A Domain Is a Child of an Axis

A domain represents the collection of elements along a given axis.

A domain element may appear as the child of any number of axis elements. For example, "Equity Securities [Domain]" could be the child of both "Trading Securities [Axis]" and "Available-for-Sale Securities [Axis]".

An axis element must have no more than one domain child anywhere in the taxonomy. For example, "Trading Securities [Axis]" cannot have the child "Equity Securities [Domain]" in one place and the child "Financial Instrument [Domain]" in another.

5.1.5 Domain Members Are Children of a Domain

Domain members are the individual elements that appear along an axis. Because every domain is automatically the default "total" domain member, preparers must not create an explicit "total" domain member as a new element. The domain-member relationship is analogous to the calculation relationship: the domain represents the sum of values of its member children.

A domain member element may appear as the child of any number of domain elements.

Returning to Figure 37, if a business entity reports a fair value for the "Major Types of Debt and Equity Securities [Domain]", as well as a value for each of the three members, then the value for the domain should be the sum of the three other values. But there the analogy ends; XBRL-enabled software does not perform a consistency check to determine that all values reported for specified domain members (in this example, the values for the three major types of debt and equity securities) sum to the total value.

5.1.6 Line Items Are Children of the Line Items Abstract Element

For reasons internal to the XBRL specification, in the dimensional relationships, both domain members and line items are organized into hierarchies using the domain-member relationship. However, domain members and line items are not interchangeable. A domain member cannot be used to tag data in the same way that other elements can.

5.1.7 Each Domain Element Is the Default Member of an Axis

A line item that is not specifically associated with a domain member is assumed to be the total for that domain. That is, if a line item is not reported as being a disaggregated amount associated with some other member, then it is assumed to be the default total. If an instance document contains a value that is not otherwise specified to relate to a specific domain member, then XBRL-enabled software will treat it as an amount for the reporting entity as a whole. In short, if the preparer ignores an axis of a table in an instance document, then XBRL software ignores that axis too.

Some software tools show the domain element as the child of the axis element twice: once as the domain element, and again as the default. This is technically correct. Figure 39 includes an asterisk next to a domain element as a user might see it twice in certain software products. Because an axis element must have no more than one domain child anywhere in the taxonomy, it follows that there can only be one default.

The example in Figure 36 has been discussed from a theoretical perspective, but how is it represented in the XBRL US GAAP Taxonomy? The taxonomy contains a table for this disclosure, including many elements not used in the example. Figure 39 presents a copy of the table containing only the necessary elements in the desired order; this process is described in Section 6, Creating Extensions.

Figure 39 Available-for-Sale Securities Table in the XBRL US GAAP Taxonomy (Dimension Relationships)

Figure 40 shows how XBRL-enabled software might display the table as constructed in Figure 39 above. The exact view will vary based on the software used.

Figure 40 Available-for-Sale Securities Table in the XBRL US GAAP Taxonomy (Tabular)

5.1.8 Calculations within Tables

Calculations within tables follow the same rules as calculations outside tables except that the relationships can only be defined between line items (see Section 4, Using Taxonomy Calculations). Calculations do not operate across domain members. In a table such as Figure 40 above, with line items on the vertical axis and domain members across the horizontal axis, this means that an "implicit total" such as that indicated in the rightmost column is not checked for consistency with the sum of disaggregated values in the other columns (US Treasury Securities, Corporate Debt Securities, and Equity Securities).

5.1.9 Presentation of a Table

XBRL tables are defined using dimension relationships, not presentation relationships. By convention, the XBRL US GAAP Taxonomy has a copy of every dimension relationship in the form of a parent-child presentation relationship to facilitate locating elements by providing all the elements within a single set of relationships. The relationship between the "line items" element and the line items is the same as in the dimension relationships. Because each of the line items has a corresponding presentation relationship, these line items can be used without any corresponding domain members. That is, a line item can be used in the same manner as other numeric and textual elements in the taxonomy.

One difference between the dimension and presentation relationships is that the dimensional relationship includes the [Line Items] abstract element as the parent of the [Table] element, which is harder to understand than if the [Table] were the parent. Therefore, in the presentation relationships, whose main purpose is to facilitate locating elements, the [Table] is the parent of the [Line Items]. Other than that, Figure 39 is nearly the same as the corresponding presentation relationship shown in Figure 41.

Figure 41 Available-for-Sale Securities Table in the XBRL US GAAP Taxonomy (Presentation Relationships)

5.1.10 Rotating Axes

In the examples in this section, the vertical axis contains the line item elements, and the horizontal axis disaggregates the elements by type of security. Figure 42 shows ABC Company's table of debt and equity securities from note 3 of its financial statements.

Figure 42 ABC Company and Subsidiaries, Note 3: Marketable Debt and Equity Securities

The table structure of Figure 42 differs from the XBRL US GAAP Taxonomy table structure (Figure 40) in that the axes are switched. Some software tools allow preparers to "pivot" the axes to conform to the format of their financial report. Pivoting or flipping is purely presentational and does not change the meaning of the axes, although it may better reflect the presentation within the financial statement. Domain members remain domain members and line items remain line items, so the technical characteristics of the axes remain unchanged and the data can be interpreted by XBRL- enabled applications without regard to the original presentation.

5.1.11 Tables with More Axes

In addition to the line items axis that a table must always have, a table may have two or more other axes. The XBRL US GAAP Taxonomy has a small number of tables with more than one additional axis element. Figure 43 shows dimension relationships from relationship group "790000 – Disclosure – Segment Reporting", from the table "Schedule of Entity-Wide Revenue by Major Customers, by Reporting Segments", with four additional axis elements representing a specific entity's two major reporting segments and two major customers. The table only has one line item, representing the amount of revenue.

Figure 43 Schedule of Entity-Wide Revenue by Major Customers, by Reporting Segments (Dimension Relationships with Entity-Specific Extensions)

In this table, the reporting entity would characterize each revenue amount as to whether it refers to one or both segments, and whether it refers to one or both major customers. These characteristics are, in fact, the two axes of the table in addition to the revenue amount line item. This is usually done through a tabular layout. Figure 44 shows three of the numerous alternatives appropriate for the entity.

Figure 44 Using Multiple Axes in Alternative Layouts

The layouts differ from the XBRL US GAAP Taxonomy table only in that the axes are rotated and grouped in different ways along the horizontal and vertical axes. This rotation is purely presentational and does not change the meaning of the axes nor the line items. The rotation used by the preparer may be based on which subtotals are shown and which are not.

5.1.12 Mapping to Tables

When a preparer maps the notes to a financial statement, situations will arise when the line items and domain members of tables in the XBRL US GAAP Taxonomy do not seem to be a good match. The two most common mismatches are handled in the company's extension taxonomy:

1. A note has data in a paragraph of text, but the XBRL US GAAP Taxonomy provides the relevant line items inside of a table. Section 6.6, "Method 6: Add new relationships between elements", explains how line items from inside a table can be used anywhere.

2. A note has information in a table, but the relevant line items do not appear in a table in the XBRL US GAAP Taxonomy. Section 6.10, "Method 10: Add a new table", explains how to arrange the line items into a table.

<< PREVIOUS | NEXT >>