The proposed changes focus mostly on how XBRL dimensions are used. Currently, you can define a dimension axis for a presentation and use explicit members within the dimension to define certain properties about a particular context. This is a point of contention with data consumers, who say that it’s harder to parse certain data when preparers use contexts with dimensions for purposes outside of the scope of FASB’s Dimension Uses Style Guide. In the 2017 proposed taxonomy, FASB is looking to add an alternative to when or how dimensions are used both to allay data consumers’ concerns and to provide the same information a dimension can without relying on the dimension structure. To do this, FASB is introducing new XBRL structures called “Typed Dimensions” and “Extensible Enumerations”.

Typed Dimensions are going to work similarly to normal Explicit Dimensions. The major change is that the members that belong to Typed Dimensions won’t actually define any properties about the contexts or facts to which they belong. Rather, the members for Typed Dimensions will be explicitly used to disaggregate similar values.

Let’s take, for example, the new proposed dimension LeaseClassificationAxis. If the type of the dimension is “Positive Integers”, instead of using the member elements as explicit members for the dimension, you would use positive integers such as “1” and “2” as members. Before, the explicit members themselves had a meaning. Now, the new positive integer values mean nothing by themselves; they’re simply identifiers for that context.

Using Typed Dimensions removes the properties from the context dimensions, so these properties need to be added back in as line items. This is where the Extensible Enumerations come in.

The general idea behind the use of Extensible Enumerations in this case is to add a line item that contains facts to identify the explicit member for each context. The member that used to be attached to a context using a dimension will now be added as a fact value for an element.

To return to our example, if you have LeaseClassificationAxis as your dimension with the Typed Dimension values of “1” and “2”, you would then have a line item called “LesseeLeaseTypeEnumeratedList” with fact values of “Finance Lease” and “Operating Lease” to identify the “lease type” property for each context. This gives you a way to add a property value for that context, without having to attach it as a dimension, as shown below.

Some of the Extensible Enumerations allow for custom data, hence the term “extensible”. Enumerated List elements also have various types of data (like other XBRL elements), which will be defined on a per-element basis in the taxonomy specification.

Additionally, Extensible Enumerations won’t necessarily require a Typed Dimension to be used in conjunction with them. These enumerations could be used with standard dimensions to add more properties to a context.

The other big change coming in 2017 isn’t related to dimensions but may make it easier to build new reports in the future. Taxonomy Disclosure Templates will act as templates that issuers and preparers can use as a basis when building their reports. These are going to be a set of presentation, calculation, and definition linkbases that define what a new disclosure should look like. If you’re familiar with how Risk Return’s default linkbases work, it’s the same basic concept. An issuer would be able to just select a template and have the elements already selected for the report. Then the preparer can fill in the required fields for the disclosure or extend the template as needed. The proposed new taxonomy only includes a single Taxonomy Disclosure Template, but it’s easy to imagine that more can be added in later taxonomies.

The 2017 US GAAP taxonomy also includes updates for accounting standards and other improvements as in previous years. The full proposed taxonomy and its documentation can be found at FASB’s website.

The deadline for written comments on the proposed taxonomy is October 31, 2016.

Additional Resources

PROPOSED 2017 US GAAP Financial Reporting Taxonomy (fasb.org)

Proposed Taxonomy Style Guide - Dimension Uses (fasb.org)