Capital Stock - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
	Nov. 15, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Oct. 17, 2016	Mar. 17, 2015
Stockholders Equity Note [Line Items]
Common stock, shares authorized		200,000,000	200,000,000
Common Stock, par value		$ 0.01	$ 0.01
Preferred stock, shares authorized		10,000,000
Preferred stock, par value		$ 0.01
Stock Repurchase Program, Additional Repurchase Authorization					$ 300,000
Common stock repurchased, total purchase price		$ 4,123	$ 280,736	$ 173,024
Common stock purchased through modified dutch auction tender offer - in shares	10,617,810					5,532,708
Common stock purchased through modified dutch auction tender offer - price per share	$ 25.38					$ 29.25
Common stock purchased through modified dutch auction tender offer - total purchase price in dollars	$ 269,400					$ 161,800
Fees And Expenses Incurred Related To Modified Dutch Auction Tender Offer	$ 700					$ 700
Treasury Stock, Value, Acquired, Cost Method			$ 277,306	$ 170,132
Common stock repurchase, remaining authorized amount		$ 129,400
Treasury stock, shares		64,727,152	32,505,090
Activity related to restricted stock units vested [Member]
Stockholders Equity Note [Line Items]
Treasury shares issued		421,108	363,368	292,320
Average cost for restricted stock units		$ 3.15	$ 3.15	$ 3.15
Shares repurchased to satisfy employee withholding tax requirements resulting from certain restricted stock units becoming vested		138,080	134,122	101,682
Common stock repurchased, average cost		$ 30.24	$ 25.58	$ 28.44
Non-tender offer repurchase [Member]
Stockholders Equity Note [Line Items]
Repurchases of common stock			294,930	278,842
Common stock repurchased, total purchase price			$ 7,200	$ 7,600
Treasury Stock Acquired, Average Cost Per Share			$ 24.40	$ 27.36
Board of Director Members, Executive Officers, Related Family Foundations
Stockholders Equity Note [Line Items]
Repurchases of common stock	3,358,572
Treasury Stock Acquired, Average Cost Per Share	$ 25.38
Treasury Stock, Value, Acquired, Cost Method	$ 85,200