Employee Benefit Plans, Noncontributory Defined Benefit Pension Plan (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) Plan	Jun. 30, 2017 USD ($)
Employee Benefit Plans [Abstract]
Number of plans | Plan			2
Pension Plan [Member]
Components of net periodic benefit cost [Abstract]
Net periodic benefit cost	$ (46)	$ 31	$ (92)	$ 75
Employer contributions			0
Pension Plan [Member] | Salaries and Employee Benefits [Member]
Components of net periodic benefit cost [Abstract]
Service cost	90	84	179	175
Pension Plan [Member] | Other Expenses [Member]
Components of net periodic benefit cost [Abstract]
Interest cost	162	168	325	335
Expected return on plan assets	(345)	(273)	(689)	(547)
Net amortization and deferral	$ 47	$ 52	$ 93	$ 112