Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Allowance for doubtful accounts
Valuation and qualifying accounts
Balance at Beginning of Period	$ 20	$ 19	$ 17
Charged to Costs and Expenses	543	9	4
Charged to Other Accounts	(3)	(3)	(2)
Deductions	(2)	(5)
Balance at End of Period	558	20	19
Valuation and qualifying accounts, classified as current	17	20	19
Environmental, litigation tax and other reserves
Valuation and qualifying accounts
Balance at Beginning of Period	479	672	496
Charged to Costs and Expenses	61	119	80
Charged to Other Accounts	531	2	183
Deductions	(74)	(314)	(87)
Balance at End of Period	997	479	672
Valuation and qualifying accounts, classified as current	$ 197	$ 98	$ 287