Derivative Instruments (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Interest rate contracts
Effects of derivative instruments
Amount of loss recognized in the income statement as an increase in interest expense	$ 25,000	$ 0	$ 500,000
Cash Flow Hedging
Effects of derivative instruments
Amount of loss recognized in the income statement as an increase in interest expense	25,000		(499,000)
Cash Flow Hedging | Interest rate contracts | Interest expense Member
Effects of derivative instruments
Amount of loss recognized in the income statement as an increase in interest expense	$ 25,000		$ (499,000)