Treasury Stock - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 17, 2015	Feb. 09, 2015
Equity, Class of Treasury Stock [Line Items]
Remaining authorized repurchase amount	$ 113,600,000
Modified Dutch Auction Authorized Amount				200,000,000
Fees and Expenses Modified Dutch Auction			800,000
Repurchase of common stock under share repurchase authorization	(162,630,000)	(113,000)
Treasury shares issued (shares)	121,766
Issuance of treasury shares, average cost per share (usd per share)	$ 6.30
Treasury stock (shares)	27,041,597
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			$ 161,800,000
2014 Stock Incentive Plan [Member]
Equity, Class of Treasury Stock [Line Items]
Average cost per share of treasury stock acquired	$ 57.53
Shares repurchased to satisfy minimum employee withholding tax requirements resulting from the vesting of such restricted stock units (shares)	44,122