Derivatives (Details 4) - Not Designated as Hedging Instrument - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016
Interest rate contracts
Derivative [Line Items]
Derivative liabilities	$ (2,158)	$ (2,530)	$ (5,422)
Foreign currency contract
Derivative [Line Items]
Derivative assets	654	(112)	1,391
Other long term liabilities | Interest rate contracts
Derivative [Line Items]
Derivative liabilities	(2,158)	(2,530)	(5,422)
Short term assets | Foreign currency contract
Derivative [Line Items]
Derivative assets	$ 654	$ (112)	$ 1,391