Components of Basic and Diluted Earnings Per Share (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Net income available for common stockholders	$ 96	$ 108	$ 155	$ 167
Weighted average outstanding shares of common stock	156.9	163.4	157.7	164.4
Dilutive effect of employee stock options, restricted stock and other stock awards	2.5	2.9	2.5	3.0
Common stock and common stock equivalents	159.4	166.3	160.2	167.4
Basic	$ 0.61	$ 0.66	$ 0.98	$ 1.02
Diluted	$ 0.60	$ 0.65	$ 0.97	$ 1.00

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of share based payment arrangements using the treasury stock method.

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The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

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