Fair Value Measurements Derivative Financial Instruments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Derivative [Line Items]
Cash held as collateral	$ 3,961		$ 3,961		$ 5,409
Foreign Currency Derivatives Contracts [Member]
Derivative [Line Items]
Notional amount	43,067		43,067		43,431
Fair value	266		266		(208)
Foreign Currency Derivatives Contracts [Member] | Other Expense [Member]
Derivative [Line Items]
Gain (losses) on derivative instruments	(393)	$ 40	88	$ 33
Foreign Currency Derivatives Contracts [Member] | Not Designated as Hedging Instrument [Member] | Prepaid Expenses and Other Current Assets [Member]
Derivative [Line Items]
Derivative assets	287		287		102
Foreign Currency Derivatives Contracts [Member] | Not Designated as Hedging Instrument [Member] | Accrued Expenses And Other Liabilities [Member]
Derivative [Line Items]
Derivative liabilities	$ 21		$ 21		$ 310