Common and Preferred Stock (Additional Information) (Detail) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended	9 Months Ended
	Dec. 01, 2015	Oct. 31, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Equity [Abstract]
Increase in share repurchase authorized amount	$ 300,000
Purchase of common stock (in shares)			738,953	2,400,000
Repurchase of common stock, including subsequent settlements			$ 55,000	$ 179,400
Purchase of common stock		$ 4,300	57,272	$ 177,772
Remaining authorized repurchase amount			$ 580,000
Common stock, authorized (in shares)			150,000,000		150,000,000
Common stock, par value (in dollars per share)			$ 0.01		$ 0.01
Preferred stock, authorized (in shares)			5,000,000		5,000,000
Preferred stock, par value (in dollars per share)			$ 0.01		$ 0.01
Preferred stock, issued (in shares)			0		0