Income Taxes (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Income Tax Disclosure [Abstract]
Income tax expense (benefit)	$ (20)	$ 10	$ 119	$ 249
Effective tax rate (in percent)	46.50%	15.20%	20.10%	22.90%
Statutory income tax rate (in percent)	35.00%		35.00%