Derivative Instruments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Effects of derivative instruments
Amount of Gain Recognized in OCI on Derivatives (Effective Portion)	$ 434	$ (441)
Cash Flow Hedging
Effects of derivative instruments
Amount of Gain Recognized in OCI on Derivatives (Effective Portion)	335
Amount of Loss (Gain) Reclassified from Accumulated OCI into Income (Effective Portion)	226
Cash Flow Hedging | Interest expense Member
Effects of derivative instruments
Amount of Loss (Gain) Reclassified from Accumulated OCI into Income (Effective Portion)	226
Cash Flow Hedging | Interest rate contracts | Interest expense Member
Effects of derivative instruments
Amount of Gain Recognized in OCI on Derivatives (Effective Portion)	$ 335