Statements of Consolidated Changes in Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Class of Stock [Line Items]
Common stock dividends per share	$ 0.00	$ 0.60	$ 0.60
Preferred stock dividends per share	$ 1.32	$ 1.76	$ 1.66