Company Operations and Summary of Significant Accounting Policies - Basic and Diluted EPS (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Basic net income per share:
Net income	$ 7,113	$ (5,767)	$ (6,908)	$ (1,512)	$ 1,139	$ (4,361)	$ (1,755)	$ 12,367	$ (7,074)	$ 7,390	$ 4,993
Less: income allocated to participating securities										(17)	(28)
Net income allocated to common stockholders										7,373	4,965
Weighted average common shares outstanding — basic									34,451	33,836	33,068
Net income per share — basic	$ 0.20	$ (0.17)	$ (0.20)	$ (0.04)	$ 0.03	$ (0.13)	$ (0.05)	$ 0.37	$ (0.21)	$ 0.22	$ 0.15
Diluted net income per share:
Net income	7,113	(5,767)	(6,908)	(1,512)	1,139	(4,361)	(1,755)	12,367	(7,074)	7,390	4,993
Less: income allocated to participating securities										(16)	(27)
Net income allocated to common stockholders										$ 7,374	$ 4,966
Weighted average common shares outstanding — basic									34,451	33,836	33,068
Dilutive securities										1,111	634
Weighted average common shares outstanding — diluted									34,451	34,947	33,702
Net income per share — diluted	$ 0.20	$ (0.17)	$ (0.20)	$ (0.04)	$ 0.03	$ (0.13)	$ (0.05)	$ 0.36	$ (0.21)	$ 0.21	$ 0.15