Earnings Per Share (Computation Of Basic And Diluted Earnings Per Share) (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Earnings Per Share [Line Items]
Net income for basic EPS	$ 280	$ 82	$ 336	$ 141
Convertible note interest, net of tax	1	2	4	5
Net income for diluted EPS	$ 281	$ 84	$ 340	$ 146
Basic weighted average shares outstanding	106.8	105.4	106.5	105.1
Options, warrants and non-vested stock	2.3	2.3	2.2	2.6
Convertible debt	8.9	21.2	14.0	21.2
Diluted weighted average shares outstanding	118.0	128.9	122.7	128.9
Earnings per share:
Basic	$ 2.62	$ 0.78	$ 3.16	$ 1.34
Diluted	$ 2.38	$ 0.65	$ 2.77	$ 1.14