Equity (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Stockholders' Equity Note [Abstract]
Stock repurchase program, authorized amount	$ 500.0
Stock repurchase program, remaining authorized repurchase amount	$ 142.8
Treasury stock, average price paid per share	$ 57.17	$ 40.67	$ 53.19	$ 39.12

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

No definition available.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration