Net Profit per Share - Computation of Basic and Diluted Net Profit Per Share Attributable to Common Stock (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Numerator:
Net income	$ 144,020	$ 145,832	$ 64,295
Denominator:
Weighted-average common shares outstanding, basic (shares)	79,998	80,754	80,551
Dilutive effect of potential common stock (shares)	1,523	1,529	2,038
Total shares, diluted (shares)	81,521	82,283	82,589
Net income per share, basic (usd per share)	$ 1.80	$ 1.81	$ 0.80
Net income per share, diluted (usd per share)	$ 1.77	$ 1.77	$ 0.78