Earnings Per Share - Summary of Earnings Per Share, Basic and Diluted (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Earnings Per Share [Abstract]
Net income	$ 98,678	$ 88,549	$ 192,831	$ 163,658
Denominator for basic and diluted earnings per share:
Denominator for basic earnings per share	91,904	82,996	91,828	82,867
Dilutive securities	2,146	2,821	2,164	2,890
Denominator for diluted earnings per share	94,050	85,817	93,992	85,757
Basic earnings per share	$ 1.07	$ 1.07	$ 2.10	$ 1.97
Diluted earnings per share	$ 1.05	$ 1.03	$ 2.05	$ 1.91