Earnings Per Share - Reconciles Numerator and Denominator of Basic and Diluted Earnings Per Share Computations for Net Income (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
Numerator for EPS:
Net income	$ 15,582	$ 14,407	$ 17,029	$ 11,959	$ 4,406	$ 8,256	$ 7,777	$ 9,873	$ 58,977	$ 30,312	$ 20,109
Less: Preferred stock dividends									(29)	(287)	(20)
Income available to common stockholders									$ 58,948	$ 30,025	$ 20,089
Denominator for EPS:
Weighted average common shares outstanding									35,866	39,614	39,184
Plus: Assumed conversion of stock-based compensation									1,531	513	770
Assumed conversion of preferred stock									379	489	488
Weighted average diluted common shares outstanding									37,776	40,616	40,442
Basic earnings per common share	$ 0.46	$ 0.43	$ 0.47	$ 0.30	$ 0.11	$ 0.21	$ 0.20	$ 0.24	$ 1.64	$ 0.76	$ 0.51
Diluted earnings per common share	$ 0.44	$ 0.40	$ 0.44	$ 0.29	$ 0.11	$ 0.20	$ 0.19	$ 0.24	$ 1.56	$ 0.75	$ 0.50
Weighted average number of antidilutive shares									518	818	2,553