Income Taxes - Additional information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Line Items]
Effective income tax rates	26.00%
Statutory income tax rates	21.00%	35.00%
Cumulative loss, period	3 years
Valuation allowance	$ 25,079,000	$ 10,911,000
Operating loss carryforward period	20 years
Net operating losses limitation percentage of taxable income	80.00%
Net operating loss carryforwards , expiration date	Dec. 31, 2037
Net deferred tax assets, before valuation allowance	$ 7,200,000
Uncertain tax positions	143,000	76,000	$ 83,000
Accrued interest and penalties related to uncertain tax positions	15,000	11,000	$ 8,000
Unremitted earnings	600,000
Federal
Income Tax Disclosure [Line Items]
Net operating loss carryforwards	104,800,000
Net operating loss carryforwards, subject to 20-year carryforward period		52,100,000
Net operating loss carryforwards, carried forward indefinitely		52,700,000
State
Income Tax Disclosure [Line Items]
Net operating loss carryforwards	85,700,000
Foreign
Income Tax Disclosure [Line Items]
Net operating loss carryforwards	25,500,000	4,600,000
Operating loss carryforwards, valuation allowance	$ 25,100,000	$ 4,500,000
China
Income Tax Disclosure [Line Items]
Statutory income tax rates	25.00%
INDIA
Income Tax Disclosure [Line Items]
Statutory income tax rates	30.00%
U.K.
Income Tax Disclosure [Line Items]
Statutory income tax rates	19.00%
NETHERLANDS
Income Tax Disclosure [Line Items]
Statutory income tax rates	25.00%
SWEDEN
Income Tax Disclosure [Line Items]
Statutory income tax rates	22.00%
NORWAY
Income Tax Disclosure [Line Items]
Statutory income tax rates	22.00%