Schedule II - Valuation And Qualifying Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Doubtful accounts
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	$ 7	$ 14	$ 6
Charged to costs and expenses	1	(6)	8
Charged to other accounts	0	0	0
Deductions	(3)	(1)	0
Balance at end of period	5	7	14
Cash discounts
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	2	1	1
Charged to costs and expenses	34	37	36
Charged to other accounts	0	0	0
Deductions	(33)	(36)	(36)
Balance at end of period	3	2	1
Income tax valuation allowance
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	70	1,023	995
Charged to costs and expenses	0	0	1
Charged to other accounts	0	0	112
Deductions	(19)	(953)	(85)
Balance at end of period	$ 51	$ 70	$ 1,023