Stockholders' Equity - Schedule of Stock Repurchases (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2017	Sep. 30, 2016
Stockholders Equity [Line Items]
Total cost		$ 155,285
Stock Repurchase Program
Stockholders Equity [Line Items]
Shares of common stock repurchased and retired	1,599	4,366	85
Average price paid per share	$ 32.98	$ 35.55	$ 34.12
Total cost	$ 52,741	$ 155,198	$ 2,903