Restatement of the Consolidated Financial Statements - Schedule of Effect of Restatement on Company's Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Prepaid expenses and other current assets	$ 2,080	$ 872
Total current assets	26,758	25,934
Total assets	50,843	50,577
Accrued expenses	2,877	3,430
Deferred revenue	5,708	4,167
Total current liabilities	12,677	9,839
Total liabilities	15,977	13,515
Accumulated deficit	(244,954)	(243,311)
Total stockholders' equity	34,316	36,512
Total liabilities and stockholders' equity	50,843	50,577
As Previously Reported [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Prepaid expenses and other current assets	2,826	1,674
Total current assets	27,504	26,736
Total assets	51,589	51,379
Accrued expenses	3,168	4,158
Deferred revenue	1,253	1,336
Total current liabilities	8,513	7,736
Total liabilities	11,813	11,412
Accumulated deficit	(240,044)	(240,406)
Total stockholders' equity	39,226	39,417
Total liabilities and stockholders' equity	51,589	51,379
Restatement Adjustments [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Prepaid expenses and other current assets	(746)	(802)
Total current assets	(746)	(802)
Total assets	(746)	(802)
Accrued expenses	(291)	(728)
Deferred revenue	4,455	2,831
Total current liabilities	4,164	2,103
Total liabilities	4,164	2,103
Accumulated deficit	(4,910)	(2,905)
Total stockholders' equity	(4,910)	(2,905)
Total liabilities and stockholders' equity	$ (746)	$ (802)