Consolidated Statements of Capital (Parenthetical) (USD $) In Millions, except Per Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Statement Of Stockholders Equity [Abstract]
Common equity, shares authorized	400.0	400.0	400.0	400.0
Common equity, par value	$ 1	$ 1	$ 1	$ 1