Earnings Per Share - Computation of Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Numerator
Numerator for basic and diluted earnings per share - Net income attributable to common stockholders	$ 61,687	$ 49,303	$ 137,558	$ 179,057
Denominator
Denominator for basic earnings per share - weighted average shares outstanding (in shares)	52,042	54,055	52,555	54,869
Effect of dilutive securities - stock options and other stock units (in shares)	393	625	491	590
Denominator for diluted earnings per share - adjusted weighted average shares outstanding (in shares)	52,435	54,680	53,046	55,459
Earnings per share:
Basic (in dollars per share)	$ 1.19	$ 0.91	$ 2.62	$ 3.26
Diluted (in dollars per share)	$ 1.18	$ 0.90	$ 2.59	$ 3.23