Equity and Earnings Per Share (Schedule of Basic and Diluted Earnings Per Share) (Detail) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended					9 Months Ended
	Sep. 30, 2012		Jun. 30, 2012	Mar. 31, 2012	Sep. 30, 2011	Sep. 30, 2012		Sep. 30, 2011
Net income from continuing operations	$ 112				$ 80	$ 242		$ 237
Net income from discontinued operations	0				0	0		1
Net Income	$ 112		$ 62	$ 68	$ 80	$ 242		$ 238
Weighted average shares outstanding for basic computation:
Average shares outstanding	229,000,000				226,000,000	228,000,000		226,000,000
Adjustment to shares outstanding
Weighted Average Shares Outstanding for Computation of Basic Earnings Per Share of Common Stock	229,000,000				226,000,000	228,000,000		226,000,000
Net effect of potentially dilutive shares	2,000,000	[1]				1,000,000	[2]
Weighted Average Shares Outstanding for Computation of Diluted Earnings Per Share of Common Stock	231,000,000				226,000,000	229,000,000		226,000,000
Basic and Diluted Earnings per Share
Earnings per share of common stock from continuing operations	$ 0.49				$ 0.35	$ 1.06		$ 1.05
Earnings per share of common stock from discontinued operations
Basic and diluted earnings per share	$ 0.49				$ 0.35	$ 1.06		$ 1.05
Number of options excluded from diluted EPS calculation						0		119,766

[1] The number of options to purchase shares of common stock that were excluded from the calculation of diluted EPS because they were anti-dilutive was zero and 119,766 for the three months ended September 30, 2012 and 2011, respectively.

[2] The number of options to purchase shares of common stock that were excluded from the calculation of diluted EPS because they were anti-dilutive was zero and 119,766 for the nine months ended September 30, 2012 and 2011, respectively.