Quarterly Financial Data (Unaudited) - Summary of Quarterly Results (Detail) (USD $) In Thousands, except 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
Income Statement [Abstract]
Revenue	$ 11,536	$ 11,115	$ 10,555	$ 8,307	$ 20,091	$ 19,942	$ 17,003	$ 10,207	$ 41,513	$ 67,243	$ 134,000
Gross profit (loss)	(5,811)	(6,318)	(6,417)	(3,375)	912	2,445	11	(3,408)	(21,921)	(40)	69,635
Income (loss) from operations	(9,025)	(9,595)	(9,968)	(6,296)	(2,151)	(1,141)	(3,098)	(6,646)	(34,884)	(13,036)	54,751
Income (loss) before income taxes	(9,106)	(9,814)	(10,173)	(6,418)	(2,085)	(844)	(3,386)	(6,271)	(35,511)	(12,586)	54,633
Net income (loss)	$ (15,241)	$ (5,840)	$ (5,894)	$ (3,376)	$ (1,131)	$ 272	$ (1,312)	$ (3,367)	$ (30,351)	$ (5,538)	$ 38,059
Basic income (loss) per common share	$ (0.67)	$ (0.26)	$ (0.26)	$ (0.15)	$ (0.05)	$ 0.01	$ (0.06)	$ (0.15)	$ (1.35)	$ (0.25)	$ 1.67
Diluted income (loss) per common share	$ (0.67)	$ (0.26)	$ (0.26)	$ (0.15)	$ (0.05)	$ 0.01	$ (0.06)	$ (0.15)	$ (1.35)	$ (0.25)	$ 1.61
Weighted average common shares outstanding used in computing net income per common share:
Basic					22,538,292	22,524,611	22,518,364	22,514,539	22,572,212	22,523,951	22,852,205
Diluted					22,538,292	23,050,618	22,518,364	22,514,539	22,572,212	22,523,951	23,596,162
Weighted average common shares outstanding used in computing net loss per common share, basic and diluted:	22,599,258	22,578,608	22,560,603	22,550,378					22,572,212