Income Taxes Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Valuation and Qualifying Accounts Disclosure [Line Items]
Deferred Tax Assets, Valuation Allowance	$ 285,784	$ 249,560	$ 235,339	$ 257,728
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	(7,991)	(26,640)	(40,402)
Other adjustments [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	28,233	(12,419)	(62,791)
Additions Charged to Costs and Expenses [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	$ 7,991	$ 26,640	$ 40,402