Employee Benefit Plans - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Multiemployer plans, withdrawal obligation	$ 2,992
Multiemployer plans, current withdrawal obligation	240
Multiemployer plans, noncurrent withdrawal obligations	2,752
Expected amortization of pension prior service cost	0
Projected amortization of actuarial gains for the next fiscal year	$ 52
Other Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Maximum term of coverage for postretirement benefit plans	3 years
Actuarial loss expected to occur in the next 12 Months	$ 54
Effect of one percentage point increase on accumulated postretirement benefit obligation	55
Effect of one percentage point decrease on accumulated postretirement benefit obligation	$ 51
Employer matching contribution, allowable matching percentage based on terms of the plan (as a percent)	100.00%
Employer matching contribution (as a percent)	3.00%
Employer matching contribution, allowable matching percentage after initial match (as a percent)	50.00%
Employer matching contribution, after initial match (as a percent)	2.00%
Employer matching contribution, discretionary match	4.00%
Cliff vesting period	2 years
Amounts expensed	$ 1,468	$ 1,672
Expected amortization of pension prior service cost	$ 2
Other Postretirement Benefit Plan | Minimum
Defined Benefit Plan Disclosure [Line Items]
Medical postretirement plans, qualifying retirement age range	62 years
Other Postretirement Benefit Plan | Maximum
Defined Benefit Plan Disclosure [Line Items]
Medical postretirement plans, qualifying retirement age range	65 years
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Lump sum payout options	$ 2,436	3,375
Accumulated benefit obligation in excess of plan assets	5,762	5,499
Accumulated benefit obligation	5,762	5,499
Fair value of plan assets	$ 0	$ 0
Projected annual salary increase (as a percent)	3.00%	3.00%
Expected return on assets	$ (6,722)	$ (6,124)
Pension Plans | Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Target portfolio allocation (as a percent)	100.00%
Pension Plans | Corporate Bond Securities
Defined Benefit Plan Disclosure [Line Items]
Fixed income securities allocation (as a percent)	71.00%	72.00%
Pension Plans | US Treasury and Government
Defined Benefit Plan Disclosure [Line Items]
Fixed income securities allocation (as a percent)	19.00%	17.00%
Pension Plans | Agency Securities
Defined Benefit Plan Disclosure [Line Items]
Fixed income securities allocation (as a percent)	1.00%	1.00%
Pension Plans | Other fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fixed income securities allocation (as a percent)	9.00%	10.00%