Derivatives - Derivatives designated as cash flow hedges narrative (Details)			12 Months Ended
	Nov. 25, 2013 USD ($)	Oct. 23, 2010	Dec. 31, 2016 USD ($) position	Dec. 31, 2015 USD ($) position	Dec. 31, 2014 USD ($)	Dec. 31, 2010 USD ($)
Derivative [Line Items]
Notional Amount			$ 10,342,000	$ 10,932,000
Operating Expense [Member] | Hedging Instrument [Member]
Derivative [Line Items]
Loss on cash flow hedge ineffectiveness			0	0	$ 6,000
Cash Flow Hedging [Member] | Hedging Instrument [Member]
Derivative [Line Items]
Term	5 years
Collateral reserved for swap			$ 600,000	$ 300,000
Interest Rate Swap One [Member] | Hedging Instrument [Member]
Derivative [Line Items]
Fixed rate payment			2.59%	2.59%		2.59%
Notional Amount			$ 5,155,000	$ 5,155,000		$ 5,200,000
Term		10 years
Number of positions | position			1	1
Interest Rate Swap One [Member] | Cash Flow Hedging [Member] | Hedging Instrument [Member]
Derivative [Line Items]
Collateral reserved for swap			$ 400,000	$ 400,000
Interest Rate Swap 2 [Member] | Cash Flow Hedging [Member] | Hedging Instrument [Member]
Derivative [Line Items]
Fixed rate payment	1.43%
Notional Amount	$ 10,000,000
Interest Rate Swap [Member] | Hedging Instrument [Member]
Derivative [Line Items]
Amounts included in accumulated other comprehensive income as unrealized losses			$ 130,000	$ 195,000
Interest Rate Swap [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Number of positions | position			0	0
Interest Rate Cap [Member]
Derivative [Line Items]
Notional Amount			$ 10,000,000	$ 10,000,000
Interest Rate Cap [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Premium Paid			$ 70,000	$ 70,000
3-Month LIBOR Strike Rate			2.00%	2.00%
Interest Rate Cap [Member] | Other Operating Income (Expense) [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Change in fair value of derivative asset			$ 30,000	$ 31,000
Other Assets [Member] | Interest Rate Cap [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Fair value of derivative asset			$ 9,000	$ 39,000