Other Assets Tax Credits Narrative (Details) - USD ($)	3 Months Ended		6 Months Ended
Other Assets Tax Credits Narrative (Details) - USD ($)	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Investment Holdings [Line Items]
Investment in limited partnerships	$ 4,540,000		$ 4,540,000		$ 3,963,000
Impairment of tax credit investments	112,000	$ 94,000	225,000	$ 206,000
BOC Investment, LLC \| Historic Rehabilitation Tax Credits
Investment Holdings [Line Items]
Investment in limited partnerships	174,000		174,000		174,000
Mitchell Street Apartments Investment, LLC \| Historic Rehabilitation Tax Credits
Investment Holdings [Line Items]
Investment in limited partnerships	563,000		563,000		563,000
Tax Credit Benefits Recognized			0
Estimated Capital Contributions	5,500,000		5,500,000
Rimrock Road Investment Fund, LLC \| New Market Tax Credits
Investment Holdings [Line Items]
Investment in limited partnerships	6,800,000		6,800,000		$ 7,100,000
Tax Credit Benefits Recognized			$ 225,000	$ 188,000
New Market Tax Credit Benefit, Period of Recognition			7 years
Federal New Market Tax Credits Not Yet Recognized	$ 1,600,000		$ 1,600,000