Income Taxes Income Taxes - Deferred tax additional information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Income Taxes [Line Items]
Deferred Tax Liabilities, Net	$ (33,733)	$ (11,923)
Deferred Tax Assets, Valuation Allowance	18,079	17,494
Domestic Tax Authority
Income Taxes [Line Items]
Deferred Tax Liabilities, Net	(24,500)	(5,100)
Deferred Tax Assets, Valuation Allowance	10,700	10,600
State and Local Jurisdiction
Income Taxes [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards, State and Local	$ 8,000
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2019
Foreign Tax Authority
Income Taxes [Line Items]
Deferred Tax Assets, Valuation Allowance	$ 7,300	6,900
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2019
Deferred Tax Assets, Operating Loss Carryforwards, Foreign	$ 26,600
Deferred Tax Assets, Net	8,800	$ 10,700
SPG acquisition member | Domestic Tax Authority
Income Taxes [Line Items]
Deferred Tax Liabilities, Net	$ (34,600)