Employee Benefit Plans - Schedule of Fair Value of Plan Assets (Details) - Pension Plans - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Total	$ 166,034	$ 158,002	$ 145,065
Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fixed income securities	187,636	181,218
Investments measured at net asset value	7,459	8,662
Accounts payable - pending trades	(29,061)	(31,878)
Total	166,034	158,002
Fixed income securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fixed income securities		8,925
Fixed income securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fixed income securities	187,636	172,293
Fixed income securities | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fixed income securities	$ 0	$ 0
Corporate Bond Securities
Defined Benefit Plan Disclosure [Line Items]
Fixed income securities allocation (as a percent)	71.00%	72.00%
US Treasury and Government
Defined Benefit Plan Disclosure [Line Items]
Fixed income securities allocation (as a percent)	19.00%	17.00%
Agency Securities
Defined Benefit Plan Disclosure [Line Items]
Fixed income securities allocation (as a percent)	1.00%	1.00%
Other fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fixed income securities allocation (as a percent)	9.00%	10.00%