Summary of Significant Accounting Policies Foreign Currency (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Component of Other Operating Cost [Line Items]
Other (Income) expense, net	$ (737)	$ 632	$ (400)
Foreign Currency Gain (Loss) [Member]
Component of Other Operating Cost [Line Items]
Other (Income) expense, net	$ 2,598	$ 951	$ 1,776