Casualty, Environmental and Other Reserves - Narrative (Details) $ / shares in Units, $ in Millions		3 Months Ended								12 Months Ended
	Jun. 01, 2018 USD ($)	Dec. 31, 2018 USD ($) claim site $ / shares	Sep. 30, 2018 $ / shares	Jun. 30, 2018 $ / shares	Mar. 31, 2018 $ / shares	Dec. 31, 2017 USD ($) $ / shares	Sep. 30, 2017 $ / shares	Jun. 30, 2017 $ / shares	Mar. 31, 2017 $ / shares	Dec. 31, 2018 USD ($) claim site $ / shares	Dec. 31, 2017 USD ($) $ / shares	Dec. 30, 2016 USD ($) $ / shares	Dec. 25, 2015 USD ($)
Loss Contingencies [Line Items]
Reserves		$ 324				$ 374				$ 324	$ 374	$ 374	$ 400
Reduction in reserves										$ 26		$ 28
Earnings per share impact (in dollars per share) | $ / shares		$ 1.02	$ 1.05	$ 1.02	$ 0.78	$ 4.63	$ 0.51	$ 0.55	$ 0.39	$ 3.86	$ 6.01	$ 1.81
Casualty Reserves
Loss Contingencies [Line Items]
Reserves		$ 199				$ 228				$ 199	$ 228	$ 229	269
Individual claims expected to exceed self-insured retention amount | claim		0								0
Reduction in reserves										$ 26		28
Earnings from continuing operations										$ 19		$ 18
Earnings per share impact (in dollars per share) | $ / shares										$ 0.02		$ 0.02
Casualty Reserves | Minimum
Loss Contingencies [Line Items]
Self-insured retention amount per injury	$ 50
Casualty Reserves | Maximum
Loss Contingencies [Line Items]
Self-insured retention amount per injury	$ 75
Environmental
Loss Contingencies [Line Items]
Reserves		$ 80				90				$ 80	90	$ 95	82
Reduction in reserves										$ 0		0
Environmental impaired site | site		220								220
Other Reserves
Loss Contingencies [Line Items]
Reserves		$ 45				$ 56				$ 45	$ 56	50	$ 49
Reduction in reserves										$ 0		$ 0