Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Millions	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	AOCI Attributable to Parent	Treasury Stock
Balance, beginning of year at Dec. 31, 2015		$ 683	$ 2,153	$ 9,313	$ (315)	$ (78)
Stock-based compensation			(7)			5
Dividends paid to common stockholders				(609)
Net income	$ 66			66
Other comprehensive income	259				259
Balance, end of period at Mar. 31, 2016	11,470	683	2,146	8,770	(56)	(73)
Balance, beginning of year at Dec. 31, 2016	11,969	683	2,173	9,359	(173)	(73)
Stock-based compensation			(12)			8
Dividends paid to common stockholders				(613)
Net income	260			260
Other comprehensive income	81				81
Balance, end of period at Mar. 31, 2017	$ 11,693	$ 683	$ 2,161	$ 9,006	$ (92)	$ (65)