Earnings Per Share (Computation Of Basic And Diluted Earnings Per Share) (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Earnings Per Share [Abstract]
Net loss for basic and diluted EPS	$ (170)	$ (158)
Basic weighted average shares outstanding (in shares)	69.9	72.9
Non-vested stock (in shares)	0.0	0.0
Diluted weighted average shares outstanding (in shares)	69.9	72.9
Loss per share:
Basic (in dollars per share)	$ (2.43)	$ (2.16)
Diluted (in dollars per share)	$ (2.43)	$ (2.16)
Non-vested stock awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	1.1	1.3