Earnings Per Share (Computation Of Basic And Diluted Earnings Per Share) (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Earnings Per Share [Abstract]
Net income for basic and diluted EPS	$ 209	$ 184	$ 194	$ 318
Basic weighted average shares outstanding	90.4	102.7	93.5	104.7
Options and non-vested stock (a)	1.4	1.3	1.3	1.4
Diluted weighted average shares outstanding	91.8	104.0	94.8	106.1
Basic	$ 2.32	$ 1.80	$ 2.07	$ 3.04
Diluted	$ 2.28	$ 1.77	$ 2.05	$ 3.00
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	0.3	0.2	0.1