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
	Mar. 31, 2015	Mar. 31, 2014
Earnings Per Share [Abstract]
Net income	$ 20,906	$ 26,510
Basic Earnings Per Share, Weighted average common shares outstanding	118,540	99,797
Basic Earnings Per Share	$ 0.18	$ 0.27
Effect of dilutive securities: Restricted stock	438	501
Effect of dilutive securities: Stock options	98	27
Diluted Earnings Per Share, Weighted average shares outstanding	119,076	100,325
Diluted earnings per share	$ 0.18	$ 0.26