Earnings Per Share - Schedule of Computation of Basic and Diluted Net Income Per Common Share (Detail) (USD $) In Thousands, except Per 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]
Basic: Income available to common shareholders	$ 13,461	$ 10,403	$ 8,511	$ 8,189	$ 4,967	$ 8,051	$ 9,202	$ 6,210	$ 40,564	$ 28,430	$ 18,068
Less: Income attributable to participating securities (Series C preferred stock)									1,980	1,999	1,304
Income attributable to common shareholders									38,584	26,431	16,764
Weighted-average common shares outstanding									16,203,919	12,952,751	10,794,639
Basic earnings per share	$ 0.71	$ 0.55	$ 0.51	$ 0.59	$ 0.36	$ 0.58	$ 0.66	$ 0.45	$ 2.38	$ 2.04	$ 1.55
Diluted: Income attributable to common shareholders									$ 38,584	$ 26,431	$ 16,764
Weighted-average common shares outstanding									16,203,919	12,952,751	10,794,639
Stock options outstanding									337,371	108,537	37,754
Warrants									82,824	51,503	28,535
Weighted-average common shares outstanding - assuming dilution									16,624,114	13,112,791	10,860,928
Diluted earnings per share	$ 0.69	$ 0.54	$ 0.49	$ 0.58	$ 0.35	$ 0.57	$ 0.65	$ 0.44	$ 2.32	$ 2.02	$ 1.54