Employee Benefits - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Number of consecutive years of employee's compensation	5 years
Number of total years of employee's compensation	10 years
Service cost	$ 0
Expected long-term rate of return on plan assets	3.45%	4.80%	7.50%
Accumulated benefit obligation	$ 117,500,000	$ 113,700,000
Projected benefit obligation	117,506,000	113,679,000	$ 95,200,000
Net periodic benefit cost	1,783,000	867,000	(250,000)
Amounts before tax reflected in accumulated other comprehensive income (loss)	19,572,000	23,106,000
Settlement charge	833,000	0	0
Purchases of level 3 plan assets	0	0
Transfers of level 3 plan assets	0	0
Supplemental Executive Retirement Plan
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	5,600,000	5,300,000
Net periodic benefit cost	700,000	400,000	500,000
Amounts before tax reflected in accumulated other comprehensive income (loss)	2,400,000	2,400,000	1,900,000
Settlement charge	$ 200,000
Thrift Plan
Defined Benefit Plan Disclosure [Line Items]
Contributions to the Thrift Plan	3.50%
Compensation expense	$ 2,400,000	$ 2,000,000.0	$ 1,700,000
Equities and alternatives | Minimum
Defined Benefit Plan Disclosure [Line Items]
Targeted asset allocation percentage	5.00%
Equities and alternatives | Maximum
Defined Benefit Plan Disclosure [Line Items]
Targeted asset allocation percentage	15.00%
Fixed income | Minimum
Defined Benefit Plan Disclosure [Line Items]
Targeted asset allocation percentage	85.00%
Fixed income | Maximum
Defined Benefit Plan Disclosure [Line Items]
Targeted asset allocation percentage	95.00%