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, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Earnings Per Share [Abstract]
Net income for basic EPS	$ 184	$ 192	$ 318	$ 222
Convertible note interest, net of tax	0	0	0	1
Net income for diluted EPS	$ 184	$ 192	$ 318	$ 223
Basic weighted average shares outstanding	102.7	103.9	104.7	105.2
Options and non-vested stock (a)	1.3	2.0	1.4	2.0
Convertible debt	0.0	4.0	0.0	4.0
Diluted weighted average shares outstanding	104.0	109.9	106.1	111.2
Basic	$ 1.80	$ 1.84	$ 3.04	$ 2.11
Diluted	$ 1.77	$ 1.74	$ 3.00	$ 2.00
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	0.3		0.1