ASC 810, which adopted the requirements of SFAS 160, requires noncontrolling interest to be reported within equity but separately from the parent's equity. Consolidated balance sheets therefore show a subtotal for equity attributable to the parent, tagged StockholdersEquity in XBRL, followed by noncontrolling interest and a grand total tagged StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest. The SEC taxonomy notes that StockholdersEquity excludes temporary equity and is sometimes called permanent equity.
Regulation S-X Rules 5-02.28 through 5-02.30 set out the parent's equity captions: preferred stock that is not mandatorily redeemable, each class of common stock, and other stockholders' equity, which covers additional paid-in capital, retained earnings, and accumulated other comprehensive income. Rule 5-02.31 is the caption for noncontrolling interests in consolidated subsidiaries. Preferred stock that must be redeemed, or whose redemption is outside the company's control, is presented under Rule 5-02.27 outside stockholders' equity and is not part of this figure.
This is the equity figure that matches earnings attributable to the parent, which makes it the right denominator for return on equity and the starting point for book value per share. Using total equity instead can overstate a shareholder's claim at companies with large partly owned subsidiaries, such as some utilities, real estate groups, and holding companies. For common-equity measures, preferred stock is subtracted as well.