Net Income Per Share - Summary of Table Reconciling Basic and Diluted Net Income Per Share (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Earnings Per Share [Abstract]
Net income	$ 29,134	$ 23,948	$ 74,417	$ 76,371
Basic Earnings Per Share, Weighted average common shares outstanding	111,428	100,645	105,086	100,901
Basic Earnings Per Share	$ 0.26	$ 0.24	$ 0.71	$ 0.76
Effect of dilutive securities: Restricted stock	446	454	428	424
Effect of dilutive securities: Stock options	73	32	45	26
Diluted Earnings Per Share, Weighted average shares outstanding	111,947	101,131	105,559	101,351
Diluted earnings per share	$ 0.26	$ 0.23	$ 0.70	$ 0.75