Commitments - Additional Information (Detail) - USD ($)	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Contractual Obligation [Line Items]
Agreement for purchase of equipment	$ 3,400,000	$ 3,321,000
Laboratory and Computer Equipment [Member] | Wells Fargo Equipment Finance [Member]
Contractual Obligation [Line Items]
Agreement for purchase of equipment	1,500,000
Laboratory and Computer Equipment [Member] | Wells Fargo Equipment Finance [Member] | 36 Month Term [Member]
Contractual Obligation [Line Items]
Agreement for purchase of equipment	$ 200,000
Lease term period	36 months
Buyout option	$ 1
Interest rate	3.61%
Laboratory and Computer Equipment [Member] | Wells Fargo Equipment Finance [Member] | 60 Month Term [Member]
Contractual Obligation [Line Items]
Agreement for purchase of equipment	$ 1,300,000
Lease term period	60 months
Buyout option	$ 1
Interest rate	4.08%
Other Lease Agreement [Member] | Computer Equipment and Computer Software [Member]
Contractual Obligation [Line Items]
Agreement for purchase of equipment	$ 1,900,000
Buyout option	$ 1
Weighted average interest rate	5.47%
Minimum [Member] | Other Lease Agreement [Member] | Computer Equipment and Computer Software [Member]
Contractual Obligation [Line Items]
Lease term period	36 months
Interest rate	4.00%
Maximum [Member] | Other Lease Agreement [Member] | Computer Equipment and Computer Software [Member]
Contractual Obligation [Line Items]
Interest rate	13.50%