Reconciliation of Income and Number of Shares Used to Calculate Basic and Diluted Earnings per Share (EPS) - Summary of Reconciliation of Income and Number of Shares Used to Calculate Basic and Diluted Earnings per Share (EPS) (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Earnings Per Share [Abstract]
EPS, income	$ 10,172	$ 7,970	$ 8,281	$ 592	$ (20,098)	$ 10,936	$ 20,083	$ 26,392	$ 27,015	$ 37,313	$ (50,451)
Basic EPS, shares									119,284,468	117,721,135	116,081,590
Basic earnings per share:	$ 0.08	$ 0.07	$ 0.07	$ 0.00	$ (0.17)	$ 0.09	$ 0.17	$ 0.23	$ 0.23	$ 0.32	$ (0.43)
Stock options and restricted stock, shares									1,940,082	1,372,455	0
Stock options and restricted stock, per share amount	$ (0.01)				$ (0.01)				$ (0.01)	$ (0.01)	$ 0.00
Diluted EPS, shares									121,224,550	119,093,590	116,081,590
Diluted earnings per share:	$ 0.08	$ 0.07	$ 0.07	$ 0.00	$ (0.17)	$ 0.09	$ 0.17	$ 0.22	$ 0.22	$ 0.31	$ (0.43)