Fair Value Measurements and Derivative Instruments (Derivative Instruments) (Details) - USD ($)	Dec. 31, 2016	Sep. 30, 2016	Jan. 31, 2016	Dec. 31, 2015
Derivative [Line Items]
Total net derivative liability	$ (1,492,000)			$ (3,671,000)
Total derivative assets
Derivative [Line Items]
Derivative asset	2,225,000			1,716,000
Total derivative liabilities
Derivative [Line Items]
Derivative liability	(3,717,000)			(5,387,000)
Derivatives designated as hedging instruments | Foreign exchange contracts | Other current assets and prepayments
Derivative [Line Items]
Derivative asset	487,000			217,000
Derivatives designated as hedging instruments | Foreign exchange contracts | Accounts payable and accrued liabilities
Derivative [Line Items]
Derivative liability	(136,000)			(208,000)
Derivatives designated as hedging instruments | Interest rate swaps | Other non-current assets
Derivative [Line Items]
Derivative asset	1,588,000			0
Derivatives not designated as hedging instruments | Foreign exchange contracts | Other current assets and prepayments
Derivative [Line Items]
Derivative asset	150,000			1,499,000
Derivatives not designated as hedging instruments | Foreign exchange contracts | Accounts payable and accrued liabilities
Derivative [Line Items]
Derivative liability	(3,581,000)			(5,179,000)
Cash Flow Hedging
Derivative [Line Items]
Total notional amount of outstanding contracts	$ 13,000,000			$ 13,000,000
Cash Flow Hedging | Interest rate contract
Derivative [Line Items]
Total notional amount of outstanding contracts		$ 300,000,000
Fixed interest rate		0.8826%
Term Loan | Notes due December 2020
Derivative [Line Items]
Debt face amount			$ 300,000,000