Income Taxes - Components of Deferred Income Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Deferred income tax assets:
Net operating loss carryforward	$ 649	$ 343
Deferred revenue	6,762	4,141
Deferred compensation	1,252	423
Inventory reserve	956	508
Non-qualified and non-employee stock option expense	3,393	3,094
Capitalized research and development	3,348	4,847
Alternative minimum tax carryforward	0	1,081
Research and development tax credit carryforward	2,386	2,139
Reserves, accruals, and other	1,067	1,897
Total deferred income tax assets	19,813	18,473
Deferred income tax liabilities:
Depreciation	(2,228)	(1,674)
Amortization	(1,979)	(236)
Other	(187)	0
Total deferred income tax liabilities	(4,394)	(1,910)
Net deferred income tax assets before valuation allowance	15,419	16,563
Valuation allowance	(1,700)	(500)
Net deferred income tax assets	$ 13,719	$ 16,063