Annual report pursuant to Section 13 and 15(d)

Benefit Plans and Collective Bargaining Agreements - Non-Union Employees Narrative (Details)

v3.20.4
Benefit Plans and Collective Bargaining Agreements - Non-Union Employees Narrative (Details) - 401(k) Employee Stock Ownership Plan - USD ($)
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Defined Contribution Plan Disclosure [Line Items]    
Employee maximum contribution percentage 100.00%  
Employee maximum contribution amount $ 19,500  
Minimum age to qualify under Economic Growth and Tax Relief Reconciliation Act 50 years  
Employee additional contribution eligible under economic growth and tax relief reconciliation act $ 6,500  
Employee maximum contribution eligible under economic growth and tax relief reconciliation act $ 26,000  
Employer maximum contribution percentage match 100.00% 100.00%
Matching percentage by employer of employees' gross pay 4.00% 4.00%
Matching contributions made by employer $ 400,000 $ 800,000
Employer discretionary contribution $ 0 $ 0