Consolidated Statements of Stockholders' Equity (USD $) In Millions	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, 2013		$ 683	$ 2,145	$ 9,495	$ 442	$ (91)	$ (23)
Net income (loss)	13			13
Other comprehensive income (loss)	250				250
Dividends paid to common stockholders				(338)
Stock-based compensation			(1)			6
Decrease (increase) in notes receivable from the issuance of common stock							1
Balance at Mar. 31, 2014	12,582	683	2,144	9,170	692	(85)	(22)
Balance at Dec. 31, 2014	12,794	683	2,151	9,645	400	(84)	(1)
Net income (loss)	233			233
Other comprehensive income (loss)	21				21
Dividends paid to common stockholders				(608)
Stock-based compensation			(8)			5
Decrease (increase) in notes receivable from the issuance of common stock							0
Balance at Mar. 31, 2015	$ 12,437	$ 683	$ 2,143	$ 9,270	$ 421	$ (79)	$ (1)