Consolidated Statement Of Equity - USD ($) shares in Thousands, $ in Millions	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Loss [Member]	Treasury Common Stock [Member]	Total
Balance at Dec. 31, 2016					$ (387)
Net income							$ (75)
Other comprehensive income, net of tax							61
Balance at Mar. 31, 2017					(326)
Balance at Dec. 31, 2017		$ 20	$ 5,034	$ (2,263)	(366)	$ (151)	$ 2,274
Preferred Stock Balance (in shares) at Dec. 31, 2017	19,250
Common Stock Balance (in shares) at Dec. 31, 2017		79,532				(1,091)	78,441
Impact of adoption of ASC 606 at Dec. 31, 2017				154			$ 154
Stock plans			(134)			$ 136	2
Stock plans (in shares)		835				975
Dividends on preferred stock			(53)				(53)
Net income				20			20
Other comprehensive income, net of tax					(1)		(1)
Balance at Mar. 31, 2018		$ 20	$ 4,847	$ (2,089)	$ (367)	$ (15)	$ 2,396
Preferred Stock Balance (in shares) at Mar. 31, 2018	19,250
Common Stock Balance (in shares) at Mar. 31, 2018		80,367				(116)	80,251