XBRLogic's XBRL QUALITY SCORE (and Usability Score) has been released for May, 2018 YTD, including a comparison with the same period for 2017. The results are shown here by filing software vendor, but are also available by industry, listing exchange, taxonomy, company size, etc. Overall, there has been only minor improvement (.4%) year over year for the 8 measures considered.
This scoring should be viewed as a barometer of the quality and usability of XBRL filings from the perspective of the user. These tests directly or indirectly incorporate most other quality tests (i.e. XBRL-US DCQ, AICPA’s Consistency Suite, and Hoffman’s Fundamental Accounting Concept Relations), but from the viewpoint of investors and analysts.
The components of the XBRL QUALITY SCORE are as follows:
- Tagging Error - Taxonomy
- Tagging Error - Block
- Tagging Error - Period Type
- Missing Calculation Arcs
- Invalid Subtotals
- Missing Rollups
- Signage Errors
- Invalid Labels
All tests except ‘Invalid Labels’ are made against the primary (or facing) statements – income statement, balance sheet and cash flow. All labels used in the filing are tested for validity.
The number of extensions (custom elements) used in the primary statements is deducted from the XBRL QUALITY SCORE to arrive at the XBRL USABILITY SCORE. Extensions are overused, often unnecessary and, while allowed by the SEC, undermine the comparability of financial data. They are a design flaw that any serious consumer of XBRL data must grapple with.
Technical Note. One significant change has been made from prior scoring. It is not technically an error for calculation arcs to be excluded from a table definition if those relationships have been specified elsewhere in the filing. Some companies adhere to a 'no redundancy' rule while others disclose all relationships per table, even if redundancy occurs. I believe most users prefer the latter as it avoids the potential for ambiguity when an element rolls up to multiple parents. Nonetheless, the scoring no longer penalizes a filing for missing table-specific calculation arcs if they are otherwise disclosed.