Fair Value Measurements and Derivative Instruments (Derivative Instruments) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Derivative [Line Items]
Total net derivative liabilities	$ (5,362)	$ (3,671)
Total derivative assets
Derivative [Line Items]
Total net derivative liabilities	145	1,716
Total derivative liabilities
Derivative [Line Items]
Total net derivative liabilities	(5,507)	(5,387)
Foreign exchange contracts | Derivatives designated as hedging instruments | Other current assets and prepayments
Derivative [Line Items]
Total net derivative liabilities	122	217
Foreign exchange contracts | Derivatives designated as hedging instruments | Accounts payable and accrued liabilities:
Derivative [Line Items]
Total net derivative liabilities	(661)	(208)
Foreign exchange contracts | Derivatives not designated as hedging instruments | Other current assets and prepayments
Derivative [Line Items]
Total net derivative liabilities	23	1,499
Foreign exchange contracts | Derivatives not designated as hedging instruments | Accounts payable and accrued liabilities:
Derivative [Line Items]
Total net derivative liabilities	$ (4,846)	$ (5,179)