There are a number of issues observed in regards to the use of percentages in filings.
Issue 1: Incorrect Scale Issue
A number of companies have represented the percentage with an incorrect scale. In a number of instance documents, percentages were represented on a scale of 0 to 100 as opposed to 0 to 1. For example, the value of 12% was represented as the integer 12.
A percentage item type that represents 12% should be represented as 0.12 (refer to the Edgar Filer Manual 6.6.32).
Issue 2: Incorrect Units Issue
A large number of percentage values have been represented with a unit equal to “USD”. This occurs when an element in the US GAAP taxonomy or a company extension has a data type of percentItemType and unit reference that is anything other than pure. 
All units for a percentage element with a data type of percentItemType should have a value of “pure” in the unit attribute of the fact.
<foo:taxrate contextRef=”2010-12-31” unitRef=” pureRef ” decimals=”0“>0.15</foo:taxrate>
Issue 3: Incorrect Percent Types in the Taxonomy
In the US GAAP taxonomy, there are a number of elements that are percentages but the type of the item is defined as a decimal and not as a percentItemType.
Elements with a decimal item type that actually represent a percentage should be treated as if they are a percent item type. For example 20% would be represented as the number 0.20.
The FASB 2012 taxonomy includes elements of durationItemType. If a filer has a disclosure that is represented in a value that cannot precisely be converted to ISO 8601 format, i.e. P1Y3M, a filer may likely consider three alternatives:
- Use the standard element and convert the value to ISO 8601 format (understanding this would report a rounded value and since non-numeric, no decimals attribute may be associated to convey the data was rounded).
- Create an extension element of durationString and include the value as reported (e.g. 1.2 years) rather than convert to ISO 8601 format.
- Create an extension element that is a numeric (e.g decimalItemType) and apply decimals attribute and unitRef to communicate disclosure details (e.g decimals attribute corresponding to the rounding of the fact, and a unitRef with a measure of ex: “years”).
Use option 1 and go to the nearest years, months, days, etc. to get an approximate precision that matches the intention of the disclosed numbers.
 Most percent values in extensions appear to be created using either the percent item type or the pure item type.
 In fact, any element with a data type derived from the pure item type should have a value of pure.