Casualty, Environmental and Other Reserves - Schedule of Claims Activity (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 30, 2016
Loss Contingency Accrual [Roll Forward]
Balance at beginning of period	$ 374	$ 374	$ 400
Charged to Expense	98	114	128
Change in Estimate	(26)		(28)
Payments	(122)	(114)	(126)
Balance end of period	324	374	374
Casualty Reserves
Loss Contingency Accrual [Roll Forward]
Balance at beginning of period	228	229	269
Charged to Expense	47	43	52
Change in Estimate	(26)		(28)
Payments	(50)	(44)	(64)
Balance end of period	199	228	229
Environmental Reserves
Loss Contingency Accrual [Roll Forward]
Balance at beginning of period	90	95	82
Charged to Expense	10	26	46
Change in Estimate	0		0
Payments	(20)	(31)	(33)
Balance end of period	80	90	95
Other Reserves
Loss Contingency Accrual [Roll Forward]
Balance at beginning of period	56	50	49
Charged to Expense	41	45	30
Change in Estimate	0		0
Payments	(52)	(39)	(29)
Balance end of period	$ 45	$ 56	$ 50