Computation of Basic and Diluted Net Income Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Schedule Of Earnings Per Share Basic And Diluted By Common Class [Line Items]
Net income attributable to common stockholders	$ 98,983	$ 49,557	$ 38,077
Basic EPS, Shares
Weighted average number of shares outstanding, basic	86,297	85,069	84,076
Diluted EPS, shares
Weighted average number of shares outstanding, diluted	88,182	86,135	85,706
Basic EPS, per share amount
Net income attributable to common stockholders, per share amount	$ 1.15	$ 0.58	$ 0.45
Diluted EPS, per share amount
Net income attributable to common stockholders plus assumed conversions, per share amount	$ 1.12	$ 0.58	$ 0.44
Stock Options
Effect of Dilutive Securities, shares
Stock options, Restricted stock units and restricted stock awards, shares	1,059	792	1,594
Restricted Stock Units
Effect of Dilutive Securities, shares
Stock options, Restricted stock units and restricted stock awards, shares	826
Restricted Stock Units and Restricted Stock Awards
Effect of Dilutive Securities, shares
Stock options, Restricted stock units and restricted stock awards, shares		274	36