Employee Benefit Plans - Fair value non-vested restricted shares (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Proceeds from Life Insurance Policy	$ 1,566,000	$ 507,000	$ 2,218,000
Payment to Acquire Life Insurance Policy, Investing Activities	1,566,000	507,000	2,218,000
Retirement Income Plan
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation exceeds fair value of the plan assets	(2,052,000)	(8,377,000)
Employer contribution	4,450,000	0
Accumulated other comprehensive loss, before tax	$ 6,863,000	$ 3,043,000	$ 1,888,000
Expected long-term return assumption	4.00%	7.00%	7.00%