Bank Premises and Equipment Bank Premises and Equipment (Details)	3 Months Ended	9 Months Ended
	Sep. 30, 2017 USD ($)	Sep. 30, 2017 USD ($)
Leases [Abstract]
Property Subject to or Available for Operating Lease, Gross	$ 10,600,000	$ 10,600,000
Rental Income, Nonoperating	412,000	860,000
Operating Leases, Income Statement, Depreciation Expense on Property Subject to or Held-for-lease	$ 325,000	$ 614,000