17. A method for generating markup language to represent a calculation relationship among a plurality of facts, the method carried out by one or more computing devices, the method comprising: parsing markup language of an extensible business reporting language (XBRL) instance document containing the plurality of facts, wherein each fact comprises a value tagged with one or more XBRL tags according to one of a plurality of XBRL concepts, one or more relationships among the plurality of XBRL concepts is defined by markup language contained in a taxonomy document; based on the parsing, determining that at least two facts of the plurality have the same XBRL period type but different XBRL period dates, based on the determination that the at least two facts have the same XBRL period type but different XBRL period dates, defining a fact-based calculation relationship between the at least two facts; generating markup language that represents the defined calculation relationship; and modifying the taxonomy document with the generated markup language.
17. A method for generating markup language to represent a calculation relationship among a plurality of facts, the method carried out by one or more computing devices, the method comprising: parsing markup language of an extensible business reporting language (XBRL) instance document containing the plurality of facts, wherein each fact comprises a value tagged with one or more XBRL tags according to one of a plurality of XBRL concepts, one or more relationships among the plurality of XBRL concepts is defined by markup language contained in a taxonomy document; based on the parsing, determining that at least two facts of the plurality have the same XBRL period type but different XBRL period dates, based on the determination that the at least two facts have the same XBRL period type but different XBRL period dates, defining a fact-based calculation relationship between the at least two facts; generating markup language that represents the defined calculation relationship; and modifying the taxonomy document with the generated markup language. 23. A non-transitory computer-readable medium having stored thereon computer-executable instructions for carrying out the method of claim 17 .