Common and Preferred Stock (Additional Information) (Detail) - USD ($) $ / shares in Units, $ in Thousands		6 Months Ended
	Nov. 06, 2014	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Stockholders Equity Note [Line Items]
Increase in share repurchase authorized amount	$ 300,000
Purchase of common stock (in shares)		725,993	1,490,582
Repurchase of common stock, including subsequent settlements		$ 53,900	$ 113,300
Purchase of common stock		55,971	113,592
Remaining authorized repurchase amount		$ 581,100
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
October Settlement
Stockholders Equity Note [Line Items]
Purchase of common stock		$ 200	$ 2,300