Casualty, Environmental and Other Reserves - Narrative (Details)	Jun. 01, 2018 USD ($)	May 31, 2018 USD ($)	Jun. 30, 2019 USD ($) claim site	Dec. 31, 2018 USD ($)
All Contingencies Reserves [Line Items]
Total reserves			$ 309,000,000	$ 324,000,000
Casualty
All Contingencies Reserves [Line Items]
Total reserves			$ 188,000,000	199,000,000
Self-insured retention amount, per occurrence	$ 75,000,000	$ 50,000,000
Number of individual claims expected to exceed self insured retention amount | claim			0
Environmental
All Contingencies Reserves [Line Items]
Total reserves			$ 78,000,000	80,000,000
Environmental impaired sites | site			229
Other
All Contingencies Reserves [Line Items]
Total reserves			$ 43,000,000	$ 45,000,000