Risk Management - Risk Concentrations and Interest Rate Risk (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Risk Management-Risk Concentrations and Interest Rate Risk
Derivative, Notional Amount	$ 100,000,000
Interest rate contracts
Risk Management-Risk Concentrations and Interest Rate Risk
Credit Derivative, Term	52 months
Amount of loss recognized in the income statement as an increase in interest expense	$ 25,000	$ 0	$ 500,000
Cash Flow Hedging
Risk Management-Risk Concentrations and Interest Rate Risk
Amount of loss recognized in the income statement as an increase in interest expense	25,000		(499,000)
Cash Flow Hedging | Interest expense Member | Interest rate contracts
Risk Management-Risk Concentrations and Interest Rate Risk
Amount of loss recognized in the income statement as an increase in interest expense	$ 25,000		$ (499,000)