Earnings Per Share (Computation Of Basic And Diluted Earnings Per Share) (Detail) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Basic earnings per share: [Abstract]
Net income (loss)	$ (296)	$ (1,605)	$ (338)
Less: Undistributed earnings allocated to participating securities	0	0	0
Net income (loss) available to common stockholders	$ (296)	$ (1,605)	$ (338)
Basic weighted average shares	89,013,711	118,930,282	133,001,088
Basic	$ (3.33)	$ (13.5)	$ (2.54)
Diluted earnings per share: [Abstract]
Net income (loss)	$ (296)	$ (1,605)	$ (338)
Less: Undistributed earnings allocated to participating securities	0	0	0
Less: mark-to-market gain (loss) on warrants	0	0	0
Net income (loss) available to common stockholders	$ (296)	$ (1,605)	$ (338)
Basic weighted average shares	89,013,711	118,930,282	133,001,088
Stock options	0	0	0
Diluted weighted average shares	89,013,711	118,930,282	133,001,088
Diluted	$ (3.33)	$ (13.5)	$ (2.54)
Unvested Restricted Stock And Units That Receive Nonforfeitable Dividends Or Dividend Equivalents That Have Met Service Condition	815,453	311,772	930,406
Potentially dilutive securities excluded from the diluted EPS because of antidilutive effect	4,352,031	14,127,112	16,506,438