Critical reflection on XBRL: A “customisable standard” for financial reporting?

In this paper, we discuss the dual power of XBRL to standardise and/or accommodate firms’ financial reporting practices. We first develop a conceptual framework for understanding which factors may affect the adoption of XBRL and, in turn, standardise or customise financial reporting. We then examine the XBRL implementation models adopted in two countries: Italy and the US. In Italy, XBRL is required through the application of a standard taxonomy (the Italian GAAP Taxonomy), without the ability to create and submit taxonomy extensions. Conversely, in the US, XBRL is required through the application of a standard taxonomy (the US GAAP Taxonomy), along with the ability to define individual extensions to be submitted to the SEC. We discuss the potential effects of taxonomy application on the representation of financial information. The application of a taxonomy on a “blind basis” (extensions not permitted) leads not only to the full comparability of financial data but also to a loss of idiosyncratic information. The application of a taxonomy on a “minimum basis” (individual extensions permitted) preserves specific information, but causes a potential loss of data comparability.