Derivatives Schedule of Pre-tax Effect of Hedging Derivative Instruments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Derivative [Line Items]
Interest expense	$ 1,566	$ 1,414	$ 4,543	$ 4,231
Reclassifications Out of Accumulated Other Comprehensive Income (Loss) | Gains on derivative instruments: | Interest Rate Contract
Derivative [Line Items]
Interest expense	(4)	0	(4)	0
Designated as Hedging Instrument | Reclassifications Out of Accumulated Other Comprehensive Income (Loss) | Gains on derivative instruments: | Interest Rate Contract
Derivative [Line Items]
Interest expense	4	0	4	0
Cash Flow Hedging | Interest rate swaps
Derivative [Line Items]
Amount of Gain (Loss) Recognized in OCI on Derivative (Effective Portion)	$ (11)	$ 55	$ (134)	$ 55