Casualty, Environmental and Other Reserves - Balance Sheet Presentation (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 30, 2016
Contingencies [Line Items]
Current	$ 100	$ 113
Long-term	205	211
Total	305	324	$ 374	$ 374
Casualty
Contingencies [Line Items]
Current	48	50
Long-term	139	149
Total	187	199	228	229
Personal Injury
Contingencies [Line Items]
Current	42	40
Long-term	87	103
Total	129	143
Occupational
Contingencies [Line Items]
Current	6	10
Long-term	52	46
Total	58	56
Environmental
Contingencies [Line Items]
Current	31	39
Long-term	43	41
Total	74	80	90	95
Other
Contingencies [Line Items]
Current	21	24
Long-term	23	21
Total	$ 44	$ 45	$ 56	$ 50