Quarterly Financial Data - Summarized Quarterly Information (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
Quarterly Financial Information Disclosure [Abstract]
Revenues	$ 10,544	$ 9,448	$ 8,528	$ 8,449	$ 11,843	$ 8,746	$ 10,484	$ 11,602	$ 36,979	$ 42,675	$ 43,329
Gross profit	8,309	7,247	6,077	6,029	9,473	6,254	8,083	9,158	27,662	32,968	34,881
Operating income (loss)	217	(1,144)	(5,681)	(5,134)	(1,501)	(12,980)	(7,248)	(6,101)	(11,742)	(27,830)	(27,001)
Net income (loss)	$ 205	$ (1,142)	$ (5,695)	$ (5,167)	$ (1,502)	$ (13,049)	$ (7,244)	$ (6,158)	$ (11,799)	$ (27,953)	$ (25,463)
Net (loss) per share, basic	$ 0.00	$ (0.03)	$ (0.15)	$ (0.14)	$ (0.04)	$ (0.35)	$ (0.19)	$ (0.17)	$ (0.29)	$ (0.76)	$ (0.71)
Weighted average shares outstanding, basic	45,053	41,225	38,518	37,714	37,027	37,036	37,247	36,614	40,649	36,982	35,849
Net (loss) per share, diluted	$ 0.00	$ (0.03)	$ (0.15)	$ (0.14)	$ (0.04)	$ (0.35)	$ (0.19)	$ (0.17)	$ (0.29)	$ (0.76)	$ (0.71)
Weighted average shares outstanding, diluted	45,053	41,225	38,518	37,714	37,027	37,036	37,247	36,614	40,649	36,982	35,849