Derivatives - Designated as cash flow hedges narrative (Details) - USD ($)			3 Months Ended		12 Months Ended
	Nov. 25, 2013	Oct. 23, 2010	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Derivative [Line Items]
Notional amount			$ 10,786,000		$ 10,932,000
Hedging Instrument [Member]
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
Hedging Instrument [Member] | Operating Expenses [Member]
Derivative [Line Items]
Loss on cash flow hedge ineffectiveness			0	$ 0	0
Hedging Instrument [Member] | 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			$ 300,000		$ 300,000
Hedging Instrument [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Pay rate (as a percent)			2.59%		2.59%
Notional amount			$ 5,155,000		$ 5,155,000
Amounts included in accumulated other comprehensive income as unrealized losses			$ 344,000		$ 195,000