Derivative Instruments and Hedging Activities Open Foreign Currency Contracts (Details) - Cash Flow Hedging - Foreign Exchange Contract - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Derivative [Line Items]
Notional Amounts (in U.S. Dollars)	$ 120,334	$ 74,355
Net Unrealized Gain	1,976	3,128
Australian Dollar
Derivative [Line Items]
Notional Amounts (in U.S. Dollars)	8,729	0
Net Unrealized Gain	57	0
Canadian Dollar
Derivative [Line Items]
Notional Amounts (in U.S. Dollars)	100,035	55,133
Net Unrealized Gain	1,062	2,564
Mexican Peso
Derivative [Line Items]
Notional Amounts (in U.S. Dollars)	11,570	19,222
Net Unrealized Gain	$ 857	$ 564