Summary of Significant Accounting Policies - Reconciliation of Net Income (Loss) and Weighted Average Shares Used in Computing Basic and Diluted Net Income (Loss) Per 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
Basic net income per share:
Net income applicable to common shares	$ 32,411	$ 1,772	$ 1,414	$ (889)	$ 345	$ 793	$ 134	$ 175	$ 34,708	$ 1,447	$ 344
Weighted average common shares outstanding									10,813	11,180	12,038
Basic net income per share of common stock	$ 2.99	$ 0.17	$ 0.13	$ (0.08)	$ 0.03	$ 0.07	$ 0.01	$ 0.02	$ 3.21	$ 0.13	$ 0.03
Diluted net income per share:
Net income applicable to common shares	$ 32,411	$ 1,772	$ 1,414	$ (889)	$ 345	$ 793	$ 134	$ 175	$ 34,708	$ 1,447	$ 344
Weighted average common shares outstanding									10,813	11,180	12,038
Dilutive effects of stock options and restricted stock awards									1,218	409	10
Weighted average common shares, assuming dilutive effect of stock options									12,031	11,589	12,048
Diluted net income per share of common stock	$ 2.55	$ 0.14	$ 0.12	$ (0.08)	$ 0.03	$ 0.07	$ 0.01	$ 0.02	$ 2.88	$ 0.13	$ 0.03