Consolidated Statements of Stockholders' Equity (USD $) In Millions, unless otherwise specified	Total		Common stock [Member]	Additional paid-in capital [Member]	Retained earnings [Member]	Accumulated other comprehensive income (loss) [Member]	Treasury stock [Member]	Notes receivable for the issuance of common stock [Member]
Balance at Dec. 31, 2011			$ 683	$ 2,141	$ 8,308	$ 480	$ (102)	$ (22)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	628				628
Other comprehensive income (loss), net of tax	351					351
Dividends paid to common stockholders					(162)
Stock-based compensation				5			3
(Decrease) increase in notes receivable from the issuance of common stock								1
Balance at Dec. 31, 2012	12,314		683	2,146	8,774	831	(99)	(21)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	937				937
Other comprehensive income (loss), net of tax	(389)					(389)
Dividends paid to common stockholders					(216)
Stock-based compensation				(1)			8
(Decrease) increase in notes receivable from the issuance of common stock								(2)
Balance at Dec. 31, 2013	12,651		683	2,145	9,495	442	(91)	(23)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	691	[1]			691
Other comprehensive income (loss), net of tax	(42)					(42)
Dividends paid to common stockholders					(541)
Stock-based compensation				6			7
(Decrease) increase in notes receivable from the issuance of common stock								22
Balance at Dec. 31, 2014	$ 12,794		$ 683	$ 2,151	$ 9,645	$ 400	$ (84)	$ (1)

[1] Net income in the first quarter of 2014 includes the impairment loss on the sale of CAC.