Income Taxes - Narrative (Details) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Holiday [Line Items]
Increase in valuation allowance		$ 14,400,000	$ 10,100,000
Excess stock option deductions included in net operating loss carryforwards		800,000
Research and development tax credit carryforwards		3,052,000	2,305,000
Increase in net operating losses deferred tax assets		39,420,000	31,958,000
Unrecognized tax benefits		0
Related interest and penalties accrued		0
Accrued interest related to uncertain tax positions		0
Russia | Russian Federal Tax Service
Income Tax Holiday [Line Items]
Term of tax holiday in Russia				10 years
Federal
Income Tax Holiday [Line Items]
Net operating loss carryforwards		102,100,000
Research and development tax credit carryforwards		2,100,000
State
Income Tax Holiday [Line Items]
Net operating loss carryforwards		95,600,000
Research and development tax credit carryforwards		1,500,000
Stock compensation | Federal
Income Tax Holiday [Line Items]
Net operating loss carryforwards		$ 800,000
Stock compensation | State
Income Tax Holiday [Line Items]
Net operating loss carryforwards			$ 800,000
Scenario, Forecast | ASU 2016-09 | New Accounting Pronouncement, Early Adoption, Effect
Income Tax Holiday [Line Items]
Increase in valuation allowance	$ 300,000
Increase in net operating losses deferred tax assets	$ 300,000