Employee Benefit Plans - Changes in Projected Benefit Obligations for SERP (Details) - Supplemental Employee Retirement Plan - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of year		$ 2,064	$ 2,174	$ 2,372
Net periodic benefit cost:
Interest cost		61	84	110
Actuarial loss (gain)		74	82	(32)
Total net period cost		135	166	78
Benefits paid		(276)	(276)	(276)
Benefit obligation at end of year		1,923	2,064	2,174
Funded status:
Accrued liability as of December 31		$ (1,923)	$ (2,064)	$ (2,174)
Discount rate used for benefit obligation	[1]	3.25%	4.00%	4.75%

[1] Management utilizes the Moody's 20 year AA corporate bond rates to establish the reasonableness of the discount rate used. The Company reviews and periodically updates the discount rate to reflect changes in bond market rates. The impact of the discount rate change is reflected as the actuarial gain or loss.