Consolidated Statements 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, 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)
Stock plans			(134)			$ 136	2
Stock plans (in shares)		835				975
Dividends on preferred stock ($5.56 per share)			(53)				(53)
Net income (loss)				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)
Impact of adoption of new accounting principle | Accounting Standards Update 2014-09 [Member]				154			154
Balance at Dec. 31, 2018		$ 27	4,802	(2,752)	(463)	$ (14)	$ 1,600
Common Stock Balance (in shares) at Dec. 31, 2018		106,025				(489)	105,536
Stock plans			3				$ 3
Stock plans (in shares)						(229)
Net income (loss)				(87)			(87)
Other comprehensive income, net of tax					8		8
Balance at Mar. 31, 2019		$ 27	$ 4,805	(2,749)	(534)	$ (14)	$ 1,535
Common Stock Balance (in shares) at Mar. 31, 2019		106,025				(718)	105,307
Impact of adoption of new accounting principle | Accounting Standards Update 2016-02 [Member]				11			$ 11
Impact of adoption of new accounting principle | Accounting Standards Update 2018-02 [Member]				$ 79	$ (79)		$ 79