Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Schedule Of Income Taxes [Line Items]
Federal statutory rate on loss before provision for (benefit from) income taxes	34.00%
Provision for income taxes decrease	$ 1,423,000	$ 1,423,000
Cumulative ownership percentage	50.00%
Cumulative ownership period	3 years
Net operating losses	$ 15,945,000	32,448,000	$ 33,984,000
Increase in valuation allowance	469,000	5,467,000	9,295,000
Interest or penalties related to unrecognized tax benefits	0	0	$ 0
Unrecognized tax benefits that would impact effective tax rate	1,049,000	$ 357,000
Untaxed undistributed earnings of foreign subsidiaries	12,025,000
Federal [Member]
Schedule Of Income Taxes [Line Items]
Net operating losses	184,000
Net operating loss carryforwards	$ 99,675,000
Net operating loss carryforwards expiration date	2028
State [Member]
Schedule Of Income Taxes [Line Items]
Net operating losses	$ 214,000
Net operating loss carryforwards	$ 80,937,000
Net operating loss carryforwards expiration date	2017
Federal Research and Development [Member]
Schedule Of Income Taxes [Line Items]
Research and development credits	$ 5,751,000
Research and development credits expiration year	2026
State Research and Development [Member]
Schedule Of Income Taxes [Line Items]
Research and development credits	$ 5,644,000