Commitments and Contingencies - Additional Information (Detail) $ in Thousands	1 Months Ended		3 Months Ended								12 Months Ended
	Mar. 31, 2014 USD ($) ft²	Jul. 31, 2011 USD ($) ft²	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2016 USD ($) ft² Building	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Mar. 31, 2008 ft²	Mar. 31, 2007 ft²	Mar. 31, 2001 ft²
Commitments and Contingencies [Line Items]
Lease agreement, term	8 years 1 month	11 years												2 years	5 years	10 years
Lease agreement, space | ft²		55,694									45,000			7,350	2,500	25,000
Lease agreement, expiration date		May 31, 2023									Dec. 31, 2021
Lease agreement, letter of credit issued		$ 200
Lease agreement, commencement date	Aug. 01, 2014
Future minimum rental commitment, 2017			$ 2,523								$ 2,523
Future minimum rental commitment, 2018			2,584								2,584
Future minimum rental commitment, 2019			2,491								2,491
Future minimum rental commitment, 2020			2,485								2,485
Future minimum rental commitment, 2021			2,485								$ 2,485
Lease termination description											The Company terminated the lease on the 7,350 square feet of space in the first quarter of 2015.
Lease agreement, number buildings leased | Building											4
Operating leases, rent expense											$ 2,664	$ 2,619	$ 2,735
Operating leases, deferred rent liabilities			1,792				$ 1,899				1,792	1,899	1,956
Research and development expenses			2,040	$ 1,886	$ 1,890	$ 1,539	$ 1,431	$ 1,490	$ 1,252	$ 1,568	7,355	5,740	5,609
Purchase orders, supply agreements and other contractual obligations			10,008								10,008
Licensing Agreements
Commitments and Contingencies [Line Items]
Research and development expenses											5	$ 7	$ 7
Before Amendment
Commitments and Contingencies [Line Items]
Lease agreement, space | ft²	55,694
Security deposit	$ 200
After Amendment
Commitments and Contingencies [Line Items]
Lease agreement, space | ft²	75,594
Security deposit	$ 450
Future minimum rental commitment, 2017			1,371								1,371
Future minimum rental commitment, 2018			1,371								1,371
Future minimum rental commitment, 2019			1,371								1,371
Future minimum rental commitment, 2020			1,371								1,371
Future minimum rental commitment, 2021			1,371								1,371
Expansion Space
Commitments and Contingencies [Line Items]
Lease agreement, space | ft²	19,900
Annual rent expense	$ 361
Renewal Term
Commitments and Contingencies [Line Items]
Future minimum rental commitment, 2017			984								984
Future minimum rental commitment, 2018			984								984
Future minimum rental commitment, 2019			984								984
Future minimum rental commitment, 2020			984								984
Future minimum rental commitment, 2021			$ 984								$ 984