Derivative Instruments and Hedging Activities Open Foreign Currency Contracts (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Derivative [Line Items]
Net Unrealized Gain (Loss)	$ (3,978)	$ (7,179)
Cash Flow Hedging \| Foreign Exchange Contract
Derivative [Line Items]
Notional Amounts (in U.S. Dollars)	243,921
Net Unrealized Gain (Loss)	(53)
Cash Flow Hedging \| Foreign Exchange Contract \| Australian Dollar
Derivative [Line Items]
Notional Amounts (in U.S. Dollars)	10,681
Net Unrealized Gain (Loss)	567
Cash Flow Hedging \| Foreign Exchange Contract \| Canadian Dollar
Derivative [Line Items]
Notional Amounts (in U.S. Dollars)	181,253
Net Unrealized Gain (Loss)	2,150
Cash Flow Hedging \| Foreign Exchange Contract \| Japanese Yen
Derivative [Line Items]
Notional Amounts (in U.S. Dollars)	16,882
Net Unrealized Gain (Loss)	(795)
Cash Flow Hedging \| Foreign Exchange Contract \| Mexican Peso
Derivative [Line Items]
Notional Amounts (in U.S. Dollars)	35,105
Net Unrealized Gain (Loss)	$ (1,975)