Schedule II - Valuation And Qualifying Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Doubtful accounts
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	$ 20	$ 10	$ 14
Charged to costs and expenses	(6)	9	0
Charged to other accounts	0	1	1
Deductions	(3)	0	(5)
Balance at end of period	11	20	10
Cash discounts
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	2	2	2
Charged to costs and expenses	49	45	42
Charged to other accounts	0	0	0
Deductions	(48)	(45)	(42)
Balance at end of period	3	2	2
Income tax valuation allowance
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	1,023	995	1,125
Charged to costs and expenses	0	1	(2)
Charged to other accounts	0	112	0
Deductions	(948)	(85)	(128)
Balance at end of period	$ 75	$ 1,023	$ 995