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.