Income Taxes - Additional Information (Details) - USD ($)	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Taxes Disclosure [Line Items]
Effective income tax rate reconciliation, at federal statutory income tax rate, percent			34.00%
Deferred tax balance recorded	$ 1,700,000		$ 1,704,000
Effective income tax rate			80.10%	(3.30%)	39.30%
Goodwill impairment charges				$ 37,300,000
Tax Credit, Research, Amount				600,000
Tax benefit recognized on foreign losses			$ 0
Enactment of the Tax Cuts and Jobs Act	1,700,000		1,704,000
Deferred tax asset valuation allowance	2,505,000		2,505,000	2,650,000	$ 2,349,000	$ 3,135,000
Penalties and interest accrued	0		0
Provision for income taxes			0
Net income taxes paid			1,600,000	2,100,000	2,200,000
Domestic Country [Member]
Income Taxes Disclosure [Line Items]
Deferred tax asset valuation allowance	0		0
Operating loss carryforwards	300,000		$ 300,000
Operating loss carryforwards expiration year			2037
Foreign Country [Member]
Income Taxes Disclosure [Line Items]
Deferred tax asset valuation allowance	2,400,000		$ 2,400,000
Change in deferred tax asset valuation allowance				200,000
State and Local Jurisdiction [Member]
Income Taxes Disclosure [Line Items]
Operating loss carryforwards	200,000		200,000
Operating loss carryforwards, valuation allowance	100,000		$ 100,000
Operating loss carryforwards expiration year			2021
Netherlands [Member]
Income Taxes Disclosure [Line Items]
Operating loss carryforwards	500,000		$ 500,000
Netherlands [Member] | Earliest Tax Year [Member]
Income Taxes Disclosure [Line Items]
Operating loss carryforwards expiration year			2018
Netherlands [Member] | Latest Tax Year [Member]
Income Taxes Disclosure [Line Items]
Operating loss carryforwards expiration year			2024
United Kingdom [Member]
Income Taxes Disclosure [Line Items]
Operating loss carryforwards	3,900,000		$ 3,900,000
Belgium [Member]
Income Taxes Disclosure [Line Items]
Operating loss carryforwards	$ 200,000		200,000
United States [Member]
Income Taxes Disclosure [Line Items]
Tax expense (benefit) of options exercised			300,000	$ 200,000	$ (400,000)
ASU 2016-09 [Member]
Income Taxes Disclosure [Line Items]
Additional tax expense			$ 300,000
Scenario Plan [Member]
Income Taxes Disclosure [Line Items]
Effective income tax rate reconciliation, at federal statutory income tax rate, percent		21.00%
Maximum [Member]
Income Taxes Disclosure [Line Items]
Effective income tax rate reconciliation, at federal statutory income tax rate, percent			35.00%
Effective income tax rate			40.00%
Minimum [Member]
Income Taxes Disclosure [Line Items]
Effective income tax rate			38.00%