Equity (Detail) (USD $)	3 Months Ended	9 Months Ended
Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Stockholders' Equity Note [Abstract]
Stock repurchase program, authorized amount			$ 500,000,000.0
Stock repurchase program, remaining authorized repurchase amount			$ 83,600,000
Treasury stock, average price paid per share	$ 58.26	$ 48.27	$ 55.00	$ 39.51

The remaining repurchase amount authorized by an entity's Board of Directors under a stock repurchase plan.

No definition available.

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration