Derivatives - Designated as cash flow hedges narrative (Details) - Hedging Instrument [Member] - USD ($)			3 Months Ended		9 Months Ended		12 Months Ended
	Nov. 25, 2013	Oct. 23, 2010	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Derivative [Line Items]
Pay rate (as a percent)		2.59%
Notional amount		$ 5,200,000
Term		10 years
Collateral reserved for swap			$ 400,000		$ 400,000		$ 400,000
Operating Expenses [Member]
Derivative [Line Items]
Loss on cash flow hedge ineffectiveness			0	$ 0	0	$ 0	0
Interest Rate Swap 2 [Member]
Derivative [Line Items]
Pay rate (as a percent)	1.43%
Notional amount	$ 10,000,000
Term	5 years
Collateral reserved for swap			$ 600,000		$ 600,000		$ 300,000
Interest Rate Swap [Member]
Derivative [Line Items]
Pay rate (as a percent)			2.59%		2.59%		2.59%
Notional amount			$ 5,155,000		$ 5,155,000		$ 5,155,000
Amounts included in accumulated other comprehensive income as unrealized losses			$ 293,000		$ 293,000		$ 195,000