Earnings Per Share (Computation Of Basic And Diluted Earnings Per Share) (Detail) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Basic earnings per share:
Net income (loss) available to common shareholders		$ (333)	$ (21)
Basic weighted average shares	[1]	72,089,016	85,554,236
Net income (loss) per basic common share		$ (4.62)	$ (0.24)
Diluted earnings per share:
Net income (loss) available to common shareholders		$ (333)	$ (21)
Diluted weighted average shares	[1]	72,089,016	85,554,236
Net income (loss) per diluted common share		$ (4.62)	$ (0.24)
Potentially dilutive securities excluded from the calculation of diluted EPS because of antidilutive affect		4,900,000	4,500,000

[1] Includes 0.9 million of participating securities that met the service condition and were eligible to receive nonforfeitable dividends or dividend equivalents for each of the three months ended March 31, 2020 and 2019, respectively.