Stockholders' Equity - Additional Information (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	1 Months Ended			3 Months Ended		9 Months Ended		1 Months Ended
	Sep. 13, 2013	Sep. 13, 2013 Minimum	Sep. 13, 2013 Maximum	Sep. 30, 2013 Stock Repurchase Program	Sep. 30, 2012 Stock Repurchase Program	Sep. 30, 2013 Stock Repurchase Program	Sep. 30, 2012 Stock Repurchase Program	Sep. 13, 2013 Fund program, cash	Sep. 13, 2013 Fund program Term loan
Accelerated Share Repurchases [Line Items]
Purchase of common stock, shares				1.7	2.9	9.8	4.7
Purchase of common stock, value				$ 17.7	$ 30.0	$ 102.3	$ 50.0
Shares repurchase authorized amount	400.0							150.0	250.0
Percentage of outstanding common stock repurchase	20.00%
Dutch Auction tender offer, amount	$ 250.0
Cost of shares repurchased		$ 10.00	$ 11.50
Number of shares repurchased	23
Tender maturity date	Oct. 30, 2013