Income Taxes Deferred income tax liability (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Tax Credit Carryforward [Line Items]
Deferred Tax Assets, Valuation Allowance	$ 171,456	$ 173,965
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	0	400
Deferred Tax Liabilities, Net	28,537	28,763
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration	8,000	8,000
Deferred Tax Liabilities, Goodwill and Intangible Assets	21,100	20,900
Deferred Tax Liabilities, Tax Deferred Income	500
Deferred Tax Liabilities, Regulatory Assets and Liabilities	100	100
Domestic Tax Authority [Member]
Tax Credit Carryforward [Line Items]
Deferred Tax Assets, Valuation Allowance	171,500	167,600
Foreign Tax Authority [Member]
Tax Credit Carryforward [Line Items]
Deferred Tax Assets, Valuation Allowance	$ 0	$ 6,400