Extensible Enumerations 2.0 Implementation Impact on Service Providers and XBRL Creation Software
Are You Ready?


US GAAP filers, vendors and data users have anticipated finalization of the Extensible Enumerations specification (EE 2.0) since the Financial Accounting Standards Board’s (FASB) Extensible List elements were introduced as a custom type in 2017. In early 2020 the eXtensible Business Reporting Language (XBRL) International Standards Board recommended EE 2.0, which improves on limitations of the custom type and will improve data usability; however, it requires certain changes in XBRL report creation software to be compliant, which is the primary topic of this post. The target readers are software developers responsible for developing and maintaining this software.


EE 2.0 will be implemented in the 2021 US Generally Accepted Accounting Principles (GAAP) and SEC Reporting (SRT) Taxonomies. Software used to prepare XBRL reports using those Taxonomies for submission to the U.S. Securities and Exchange Commission (SEC) will need to be modified to properly support EE 2.0. The Taxonomy updates are generally available for use in the latter part of the first quarter of each calendar year.
The Taxonomies have utilized a custom data type (extensibleListItemType) that partially met the modeling requirements until EE 2.0 reached recommendation status. As EE2.0 has now reached recommendation status all Taxonomies elements with that custom data type will be converted to the EE 2.0 data type, enumerationSetItemType, in the 2021 Taxonomy Updates. This will require changes in your software. If not implemented correctly, instance documents may not be syntactically valid when using the 2021 Taxonomies.


EE 2.0 has three primary requirements that must be met for proper instance document validation:
  1. The fact value reported must have the proper URI-based notation
    1. The extensibleListItemType, used in the 2020 and prior Taxonomies, uses a space-separated list of QNames as that was the format initially planned for the EE 2.0 specification. However, the recommendation EE 2.0 specification uses a different URI-based notation.
    2. The reported facts must be a space-separated list of unique values that are lexicographically ordered, when multiple values are reported.
    3. Here is an example fact with multiple values: http://xbrl.sec.gov/country/2021-01-31#FR http://xbrl.sec.gov/country/2021-01-31#NL http://xbrl.sec.gov/country/2021-01-31#NO http://xbrl.sec.gov/country/2021-01-31#PL
  2. The element(s) reported as a fact value must exist in a schema
    1. The element needs to be from a base taxonomy–US GAAP, SRT, and SEC taxonomies, or the extension taxonomy. The element must also be xbrli:item substitution group and not in the xbrldt:hypercubeItem or xbrldt:dimensionItem substitution groups.
  3. The element(s) reported as a fact value(s) must be present in the domain-member relationships that are defined in the Taxonomies
    1. The domain-member relationships are included in the Taxonomies. Software providers will need to include (1) capabilities to make these available for instance document support (i.e., supply the list of augmentable values for tagging reported facts) and (2) the ability to add extension elements to the domain-member relationships. Please note that this means the XBRL software will need to extend the Taxonomies’ domain-member relationships rather than recreate those relationships within their own extended linkroles (ELRs). 
EE 2.0 requires, for the use of extensible list items, the adoption of an updated data type schema (DTR) dated 2020-01-21. It includes the new data type of noLangTokenItemType, which is the base data type for the EE 2.0 data types. All US GAAP and SRT elements, including extensible list items, will change to their corresponding types in the 2020-01-21 schema. Also, two GAAP Taxonomy defined data types, gYearListItemType and flowItemType, are now defined in the common schema and therefore those two will be converted to standard types for the 2021 Taxonomies.


David M. Shaw


EE 2.0 specification: https://www.xbrl.org/Specification/extensible-enumerations-2.0/REC-2020-02-12/extensible-enumerations-2.0-REC-2020-02-12.html
EE 2.0 requirements: https://www.xbrl.org/REQ/extensible-enumerations-1.1/REQ-2016-10-12/extensible-enumerations-requirements-1.1-REQ-2016-10-12.html
EE 2.0 schema: https://www.xbrl.org/2020/extensible-enumerations-2.0.xsd
DTR: https://www.xbrl.org/dtr/2020-01-21/dtr.html
DTR schema: https://www.xbrl.org/dtr/type/2020-01-21/types.xsd