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, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Basic earnings per share:
Net income (loss) available to common shareholders		$ (106)	$ (207)	$ (439)	$ (228)
Basic weighted average shares	[1]	62,605,656	84,275,261	67,347,335	84,911,215
Net income (loss) per basic common share		$ (1.69)	$ (2.45)	$ (6.51)	$ (2.68)
Diluted earnings per share:
Net income (loss) available to common shareholders		$ (106)	$ (207)	$ (439)	$ (228)
Diluted weighted average shares		62,605,656	84,275,261	67,347,335	84,911,215
Net income (loss) per diluted common share		$ (1.69)	$ (2.45)	$ (6.51)	$ (2.68)
Potentially dilutive securities excluded from the calculation of diluted EPS because of antidilutive affect		4,900,000	4,500,000	4,900,000	4,500,000

[1] Includes 0.9 million and 1.1 million of participating securities that met the service condition and were eligible to receive nonforfeitable dividends or dividend equivalents for the three months ended June 30, 2020 and 2019, respectively. Includes 0.9 million and 1.0 million of participating securities that met the service condition and were eligible to receive nonforfeitable dividends or dividend equivalents for the six months ended June 30, 2020 and 2019, respectively.