Employee Benefit Plans - Pension Plan Asset Allocation (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Asset Category
Fair Value of Plan Assets (in dollars)	$ 91,133	$ 92,290	$ 76,210
Percentage of Plan Assets	100.00%	100.00%
Equity securities
Asset Category
Fair Value of Plan Assets (in dollars)	$ 29,348
Percentage of Plan Assets	32.00%	59.00%
Fixed income
Asset Category
Fair Value of Plan Assets (in dollars)	$ 61,635
Percentage of Plan Assets	68.00%	37.00%
Cash equivalents
Asset Category
Fair Value of Plan Assets (in dollars)	$ 150
Percentage of Plan Assets	0.00%	4.00%
Minimum | Equity securities
Asset Category
Target plan asset allocations	30.00%	50.00%
Minimum | Fixed income
Asset Category
Target plan asset allocations	60.00%	25.00%
Minimum | Cash equivalents
Asset Category
Target plan asset allocations	0.00%	0.00%
Maximum | Equity securities
Asset Category
Target plan asset allocations	40.00%	65.00%
Maximum | Fixed income
Asset Category
Target plan asset allocations	70.00%	55.00%
Maximum | Cash equivalents
Asset Category
Target plan asset allocations	5.00%	10.00%