Employee Benefit and Deferred Compensation Plans - Plan Activity (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Change in benefit obligation
Benefit obligation at beginning of year	$ 27,859,000
Benefit obligation at end of year	24,945,000	$ 27,859,000
Change in fair value of plan assets
Fair value of plan assets at beginning of year	26,913,000
Fair value of plan assets at end of year	25,206,000	26,913,000
Pension Benefits
Change in benefit obligation
Benefit obligation at beginning of year	27,859,000	28,012,000
Service cost	0	0	$ 0
Interest cost	1,043,000	1,168,000	1,216,000
Plan participants’ contributions	0	0
Actuarial (gain) loss	(2,016,000)	582,000
Benefits paid	(1,941,000)	(1,903,000)
Benefit obligation at end of year	24,945,000	27,859,000	28,012,000
Change in fair value of plan assets
Fair value of plan assets at beginning of year	26,913,000	25,241,000
Actual return on plan assets	234,000	3,575,000
Contribution by employer	0	0
Benefits paid	(1,941,000)	(1,903,000)
Fair value of plan assets at end of year	25,206,000	26,913,000	25,241,000
Funded status at end of year	$ 261,000	$ (946,000)
Weighted-average assumptions as of December 31
Discount rate used to determine the benefit obligation	4.56%	3.96%
Other Benefits
Change in benefit obligation
Benefit obligation at beginning of year	$ 1,170,000	$ 1,566,000
Service cost	8,000	9,000	12,000
Interest cost	31,000	42,000	58,000
Plan participants’ contributions	75,000	77,000
Actuarial (gain) loss	(239,000)	(328,000)
Benefits paid	(164,000)	(196,000)
Benefit obligation at end of year	881,000	1,170,000	$ 1,566,000
Change in fair value of plan assets
Funded status at end of year	$ (881,000)	$ (1,170,000)
Weighted-average assumptions as of December 31
Discount rate used to determine the benefit obligation	4.07%	3.37%