Consolidated Statement of Changes in Equity - USD ($) $ in Millions	Total	Common stock and paid-in capital [Member]	Preferred stock [Member]	Retained Earnings [Member]	Accumulated other comprehensive (loss) income [Member]	Treasury stock [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ (231)				$ (231)
Stockholders' Equity Attributable to Parent at Dec. 31, 2015	13,439	$ 21,100	$ 696	$ (8,110)		$ (16)
Net Income (Loss) Attributable to Parent	250			250
Dividends, Preferred Stock, Cash	(15)			(15)
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation	17	17
Other Comprehensive Income (Loss), Net of Tax					146
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	146
Treasury Stock, Value, Acquired, Cost Method	(14)					(14)
Stockholders' Equity Attributable to Parent at Mar. 31, 2016	$ 13,823	21,117	696	(7,875)		(30)
Common Stock, Dividends, Per Share, Declared	$ 0.00
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ (85)				(85)
Accumulated Other Comprehensive Income (Loss), Net of Tax	(341)				(341)
Stockholders' Equity Attributable to Parent at Dec. 31, 2016	13,317	21,166	0	(7,151)		(357)
Net Income (Loss) Attributable to Parent	214			214
Dividends, Preferred Stock, Cash	0
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation	21	21
Other Comprehensive Income (Loss), Net of Tax					20
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	20
Treasury Stock, Value, Acquired, Cost Method	(169)					(169)
Dividends, Common Stock, Cash	(38)			(38)
Stockholders' Equity Attributable to Parent at Mar. 31, 2017	$ 13,365	$ 21,187	$ 0	$ (6,975)		$ (526)
Common Stock, Dividends, Per Share, Declared	$ 0.08
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ (321)				$ (321)