XML 87 R60.htm IDEA: XBRL DOCUMENT v3.20.4
Retirement Plans (Other Retirement Programs) (Narrative) (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]      
401(k)/Thrift plan description For non-union employees hired prior to January 1, 2018, and eligible union employees for whom we make matching contributions, we provide a defined contribution plan (401(k)/thrift plan).    
401(k)/Thrift plan contributions $ 19 $ 20 $ 18
Defined Contribution Plan, Employer Matching Contribution, Percent of Match 50.00%    
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay 6.00%    
Railroad Retirement System [Abstract]      
Railroad Retirement System description All Railroad employees are covered by the Railroad Retirement System (the System).    
Railroad Retirement System contributions $ 569 654 710
401(k)/ Thrift Plan 2018 or later [Member]      
Defined Benefit Plan Disclosure [Line Items]      
401(k)/Thrift plan description January 1, 2018    
Defined Contribution Plan, Employer Matching Contribution, Percent of Match 100.00%    
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay 6.00%    
Defined contribution plan, additional annual employer contribution, percent of employee's gross pay 3.00%    
Collective Bargaining Agreements [Member]      
Collective Bargaining Agreements [Abstract]      
Collective bargaining agreements description Under collective bargaining agreements, we participate in multi-employer benefit plans that provide certain postretirement health care and life insurance benefits for eligible union employees    
Collective bargaining agreements premiums $ 30 $ 42 $ 50