Reconciliation of Net Income Per Share - Summary of Reconciliation of 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
Earnings Per Share [Abstract]
Net income	$ 4,485	$ 5,052	$ 4,770	$ 2,871	$ 8,206	$ 3,115	$ 7,038	$ 5,909	$ 17,178	$ 24,268	$ 20,937
Weighted average shares outstanding	17,527	17,302	17,136	17,055	17,044	17,044	17,026	16,961	17,176	17,009	16,817
Effective of dilutive stock options	290	148	36	107	106	106	113	114	84	105	136
Diluted shares outstanding	17,817	17,450	17,172	17,162	17,150	17,150	17,139	17,075	17,260	17,114	16,953
Basic net income per share	$ 0.25	$ 0.29	$ 0.28	$ 0.17	$ 0.48	$ 0.18	$ 0.41	$ 0.35	$ 1.00	$ 1.43	$ 1.24
Diluted net income per share	$ 0.25	$ 0.29	$ 0.28	$ 0.17	$ 0.48	$ 0.18	$ 0.41	$ 0.35	$ 1.00	$ 1.42	$ 1.24