A context is a set or grouping of reported facts.  Each reported fact has a taxonomy element and value in an XBRL document such as a financial report.  A context groups together all the facts that share the same reporting period and certain other characteristics.  We note the following guidance with respect to the use of contexts:

When filers report financial information in a roll-forward format or other movement analysis, the beginning balance is usually the same instant as the end of the previous period; although they may be presented on separate rows or columns, they are nevertheless the same fact, and therefore are in the same context.

• For example, a calendar-year filer presenting the statement of cash flows should use an instant context for the beginning "Cash and Cash Equivalents," which is the same as the end of the previous period.

A context that defines only the period and the facts it contains is understood to apply to the entire consolidated entity being reported on.  However, a context may be differentiated from other contexts by aspects other than reporting period. 

When filers present consolidated financial statements and separate financial disclosures for subsidiaries, businesses, or segments using the same line items, they use the same elements for those line items and create unique contexts to differentiate and designate the facts in each disaggregation.  In these circumstances, unique contexts allow common elements to be used for multiple financial disclosures included in a single Interactive Data File.

• For example, a filer that reports the same product revenue line item on a consolidated income statement as well as within disclosures for an operating segment should select the same product revenue element for both disclosures, and use one context unique to the consolidated entity and a separate context unique to the operating segment. 

See EFM 6.5.7 through 6.5.9, 6.6.1 through 6.6.11, and Staff Observations and Guidance for more information on the use of contexts.