Earnings Per Share (Computation Of Basic And Diluted Earnings Per Share) (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Earnings Per Share [Abstract]
Net income (loss) for basic and diluted EPS	$ 36	$ 143	$ (15)	$ 134
Basic weighted average shares outstanding	93.9	105.5	95.1	105.8
Options and non-vested stock (a)	1.2	1.2	0.0	1.3
Diluted weighted average shares outstanding	95.1	106.7	95.1	107.1
Basic	$ 0.39	$ 1.36	$ (0.16)	$ 1.27
Diluted	$ 0.38	$ 1.34	$ (0.16)	$ 1.25
Employee Stock Option [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount			0.8
Restricted Stock Units (RSUs) [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	0.2	0.2	1.5	0.1