Extending the core taxonomy - dimensions

With the exception of the Statement of changes in equity, the primary statement sections in the extended taxonomy do not contain any default dimensionality.  This means that by default you can only tag statements that use periods (such as current and prior) to differentiate between different columns. 

The tags in the Statement of changes in equity section of the extended taxonomy do contain dimensionality allowing the use of the same primary tag for each row and using secondary tags (dimension members) to differentiate between different columns representing different classes of equity.

See the video on this article which demonstrates the use of secondary tags.

It may however be necessary to extend the dimensionality of a primary statement for the following reasons:

1. Adding additional secondary tags to existing dimensions (for example adding a secondary tag for a class of equity that the core taxonomy does not contain).
2. Adding a dimension (core or custom) with its members to a particular primary statement. For example, adding the dimension Retrospective application and retrospective restatement [axis] dimension with its members for Currently stated and Previously stated in order to tag different columns of the same accounting concept.

Adding a secondary tag to an existing dimension

In the Statement of changes in equity, secondary tags are used to differentiate the tags for each column representing a class of equity.  If the report contains a class of equity for which there is no appropriate secondary tag, a secondary tag must be created in the extended taxonomy.

To do this, change the "Currently Tagging:" dropdown list to the Statement of changes in equity and click the configure table button:

The following form will appear:

Select the Components of equity [axis] axis (dimension) and then select a member (secondary tag) in the Members tree view which will be the parent of the new member. Click the Add button.

Adding a dimension to a primary statement

If a primary statement contains non-standard dimensionality (set of columns), you can edit the dimensionality to either:

1. Add a dimension with its members that are already defined in the core taxonomy.
2. Create and add a custom dimension with members if none exist in the core taxonomy.

Example 1

If the Statement of comprehensive income has columns for Original and Restated, change the "Currently Tagging:" dropdown list to the Statement of comprehensive income and click the Configure Table... button:

By default, this primary statement has no dimensionality:

Click Add in the Axes section:

Before we create a new dimension - we can search for existing dimensions.  Typing "resta" (stem for restatement) in the search box reveals the following dimension:

This dimension and its members would be sufficient to tag columns that represent original and restated so can be added to the report section and used as secondary tags.

Example 2

If the Statement of comprehensive income has columns for Capital and Revenue, change the "Currently Tagging:" dropdown list to the Statement of comprehensive income and click the Configure Table... button:

Click Add in the Axes section:

Searching for "reve" does not reveal any existing dimensions we can use:

We should create a new one with the label "Revenue and capital"

Select the new Axis:

Click Add in the Members' section and add members for "Total", "Revenue" and "Capital" and nest them as follows using drag and drop:

This new dimension and its members can now be used as secondary tags to differentiate the two columns.

Default members

A feature of the XBRL specification is that a default member will be assumed in the XBRL unless any other non-default member is specified.  This is convenient because when tagging, you will not need to elect a member in the dimension if the fact represents the total of all members for that dimensin. For this reason, the default member should usually represent the total or not applicable.  

Report Authority always sets the first member created as the default member.  To nominate a different member to be the default member, select the member and click the Default toggle button.