Treasury Stock - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Mar. 17, 2015	Feb. 09, 2015
Equity, Class of Treasury Stock [Line Items]
Remaining authorized repurchase amount	$ 106,000
Modified Dutch Auction Authorized Amount				$ 200,000
Fees and Expenses Modified Dutch Auction			$ 700
Repurchase of common stock under share repurchase authorization	$ (170,132)	$ (24,666)
Treasury stock (shares)	27,163,343
Common Stock Purchased Through Modified Dutch Auction Tender Offer Shares			2,766,354
Common Stock Purchased Through Modified Dutch Auction Tender Offer Price Per Share			$ 58.50
Common Stock Purchased Through Modified Dutch Auction Tender Offer Value			$ 161,800
2004 Stock Incentive Plan [Member]
Equity, Class of Treasury Stock [Line Items]
Average cost per share of treasury stock acquired	$ 56.88
Treasury shares issued (shares)	146,160
Issuance of treasury shares, average cost per share (usd per share)	$ 6.30
Shares repurchased to satisfy minimum employee withholding tax requirements resulting from the vesting of such restricted stock units (shares)	50,841
Stock Repurchase Program [Member]
Equity, Class of Treasury Stock [Line Items]
Repurchases of common stock (in shares)	139,421
Average cost per share of treasury stock acquired	$ 54.71
Repurchase of common stock under share repurchase authorization	$ (7,600)