Commitments and Contingencies - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2016 USD ($) ft²	Dec. 31, 2015 USD ($)
Commitments And Contingencies [Line Items]
Number of square feet for lease | ft²	31,577
Settlement costs	$ 156,000
ARO reserve	$ 200,000
Silicon Valley Bank Credit Facility [Member] | Revolving Credit Facility [Member]
Commitments And Contingencies [Line Items]
Line of credit agreement, extended maturity date	Aug. 31, 2016
Maximum increased borrowing amount	$ 20,000,000
Percentage of unused revolving line facility fee	0.50%
Interest rate description	The interest rate applicable to borrowings under the revolving credit facility may be based on the prime rate or LIBOR. Prime rate-based rates vary from prime rate plus 0.75% per annum to prime rate plus 1.75% per annum, while LIBOR-based rates vary from LIBOR plus 3.75% per annum to LIBOR plus 4.25% per annum.
Line of credit facility amount withdrawn	$ 0	$ 0
Letters of credit outstanding	2,700,000	$ 2,700,000
Line of credit facility borrowing capacity	$ 13,000,000
Silicon Valley Bank Credit Facility [Member] | Revolving Credit Facility [Member] | Minimum [Member] | Prime Rate [Member]
Commitments And Contingencies [Line Items]
Additional interest rate per annum	0.75%
Silicon Valley Bank Credit Facility [Member] | Revolving Credit Facility [Member] | Minimum [Member] | LIBOR Rate [Member]
Commitments And Contingencies [Line Items]
Additional interest rate per annum	3.75%
Silicon Valley Bank Credit Facility [Member] | Revolving Credit Facility [Member] | Maximum [Member] | Prime Rate [Member]
Commitments And Contingencies [Line Items]
Additional interest rate per annum	1.75%
Silicon Valley Bank Credit Facility [Member] | Revolving Credit Facility [Member] | Maximum [Member] | LIBOR Rate [Member]
Commitments And Contingencies [Line Items]
Additional interest rate per annum	4.25%