Casualty, Environmental and Other Reserves - Narrative (Details)	6 Months Ended
	Jun. 30, 2020 USD ($) claim site	Dec. 31, 2019 USD ($)
All Contingencies Reserves [Line Items]
Total reserves	$ 306,000,000	$ 305,000,000
Casualty
All Contingencies Reserves [Line Items]
Total reserves	188,000,000	187,000,000
Self-insured retention amount, per occurrence	$ 75,000,000
Number of individual claims expected to exceed self insured retention amount | claim	0
Environmental
All Contingencies Reserves [Line Items]
Total reserves	$ 75,000,000	74,000,000
Environmental impaired sites | site	220
Other
All Contingencies Reserves [Line Items]
Total reserves	$ 43,000,000	$ 44,000,000