Stockholders' Equity - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	1 Months Ended	3 Months Ended
	Oct. 31, 2012	Mar. 31, 2014	Mar. 31, 2013
Stockholders Equity Note [Line Items]
Aggregate amount of common stock authorized for repurchase	$ 300.0
Treasury stock, shares, acquired		242,608	89,751
Treasury stock acquired		$ 94.6	$ 31.6
Treasury stock acquired, average cost per share		$ 390.10	$ 351.82