Earnings Per Share (Computation Of Basic And Diluted Earnings Per Share) (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Basic earnings per share:
Net income (loss) available to common shareholders	$ (170)	$ (146)	$ (187)	$ (244)
Basic weighted average shares	84,275,261	89,131,760	84,911,215	88,865,272
Net income (loss) per basic common share	$ (2.02)	$ (1.64)	$ (2.20)	$ (2.75)
Diluted earnings per share:
Net income (loss) available to common shareholders	$ (170)	$ (146)	$ (187)	$ (244)
Diluted weighted average shares	84,275,261	89,131,760	84,911,215	88,865,272
Net income (loss) per diluted common share	$ (2.02)	$ (1.64)	$ (2.20)	$ (2.75)
Potentially dilutive securities excluded from the calculation of diluted EPS because of antidilutive affect	4,500,000	1,400,000	4,500,000	1,400,000