Segment Information (Net Revenue By Revenue Composition) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenue	$ 1,582	$ 1,160	$ 959	$ 1,449	$ 1,527	$ 1,149	$ 898	$ 1,271	$ 5,150	$ 4,845	$ 4,396
Packaged Goods and other
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenue									1,700	1,971	1,987
Digital [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenue									$ 3,450	$ 2,874	$ 2,409