Derivative Instruments and Hedging Activities Open Foreign Currency Contracts (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Derivative [Line Items]
Net Unrealized Gain (Loss)	$ (4,040)	$ (7,179)
Cash Flow Hedging | Foreign Exchange Contract
Derivative [Line Items]
Notional Amounts (in U.S. Dollars)	247,565
Net Unrealized Gain (Loss)	(2,180)
Cash Flow Hedging | Foreign Exchange Contract | Australian Dollar
Derivative [Line Items]
Notional Amounts (in U.S. Dollars)	19,414
Net Unrealized Gain (Loss)	375
Cash Flow Hedging | Foreign Exchange Contract | Canadian Dollar
Derivative [Line Items]
Notional Amounts (in U.S. Dollars)	174,648
Net Unrealized Gain (Loss)	27
Cash Flow Hedging | Foreign Exchange Contract | Japanese Yen
Derivative [Line Items]
Notional Amounts (in U.S. Dollars)	11,801
Net Unrealized Gain (Loss)	(501)
Cash Flow Hedging | Foreign Exchange Contract | Mexican Peso
Derivative [Line Items]
Notional Amounts (in U.S. Dollars)	41,702
Net Unrealized Gain (Loss)	$ (2,081)