Effect of Cash Flow Derivatives on the Balance Sheet and Income Statement, Before Tax (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Derivative Instruments Designated as Hedging Instruments [Abstract]
Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	$ 2,354	$ (259)	$ 2,373	$ (637)
Interest Rate Swap [Member]
Derivative Instruments Designated as Hedging Instruments [Abstract]
Amount of Gain (Loss) Recognized in OCI on Derivative (Effective Portion)	513	(517)	1,760	(336)
Interest Rate Swap [Member] | Interest Expense [Member]
Derivative Instruments Designated as Hedging Instruments [Abstract]
Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	246	(210)	335	(545)
Interest Rate Cap [Member]
Derivative Instruments Designated as Hedging Instruments [Abstract]
Amount of Gain (Loss) Recognized in OCI on Derivative (Effective Portion)	181	(117)	369	(201)
Interest Rate Cap [Member] | Interest Expense [Member]
Derivative Instruments Designated as Hedging Instruments [Abstract]
Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	(466)	(50)	(536)	(93)
Currency Swap 1 [Member]
Derivative Instruments Designated as Hedging Instruments [Abstract]
Amount of Gain (Loss) Recognized in OCI on Derivative (Effective Portion)	2,376	0	2,376	0
Currency Swap 2 [Member]
Derivative Instruments Designated as Hedging Instruments [Abstract]
Amount of Gain (Loss) Recognized in OCI on Derivative (Effective Portion)	0	0	0	0
Currency Swap [Member] | Interest Expense [Member]
Derivative Instruments Designated as Hedging Instruments [Abstract]
Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	207	0	207	0
Currency Swap [Member] | Other Income (Expense) [Member]
Derivative Instruments Designated as Hedging Instruments [Abstract]
Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	$ 2,368	$ 0	$ 2,368	$ 0