As companies report facts in the detailed footnotes, a number of disclosures are made as ratios. However, in a number of cases, these ratios are reported as two numbers such as $1 of debt can be converted to 2 ordinary shares. In the taxonomy these two numbers may be represented as a single ratio such as a debt conversion ratio. A number of companies have reported these as separate facts rather than as a decimal amount in their filing. In addition, the tagging of facts as decimals can be complicated if the fact value is recurring to infinity. Recurring numbers are better represented as fractions such as 1/3 as opposed 0.33333 recurring.
Per EDGAR Filer Manual, volume 2, version 28 at 6.8.14: “A ratio of values that would have the same unitRef attribute must be declared as an xsd:element with a type attribute equal to or derived from ‘percentItemType’ in a standard taxonomy schema target namespace, even though its value is not scaled by 100.”
If the numerator and denominator of a ratio have different UMs, it may be appropriate to define the item as a xbrli:pureItemType or as a perUnitItemType.
Per EDGAR Filer Manual, volume 2, version 28 at 6.8.15: “A ratio of values for which its facts would have an ISO 4217 currency in the numerator and a different ISO 4217 currency in the denominator must be declared as an xsd:element with a type equal to or derived from xbrli:pureItemType.”
Where the value reported is a repeating decimal or is infinitesimal, then the number should be expressed to an appropriate number of decimal places.
The filer should not:
- use the fraction item type for this purpose, which was prohibited from use in 2014 by the SEC
- report fractions or ratios as two separate facts, either as:
- 2 separate elements, or
- a numerator member and denominator member.
Therefore, when defining fractions using an extension element, it may be appropriate to define the item as a percentageItemType, pureItemType or as a perUnitItemType in conformity with these recommendations.