Segment Information (Net Revenue By Geographic Area) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2014
Revenue from External Customer [Line Items]
Net revenue	$ 1,308	$ 1,070	$ 815	$ 1,203	$ 1,185	$ 1,126	$ 990	$ 1,214	$ 4,396	$ 4,515	$ 3,575
North America [Member]
Revenue from External Customer [Line Items]
Net revenue from unaffiliated customers									1,907	1,956	1,510
International [Member]
Revenue from External Customer [Line Items]
Net revenue from unaffiliated customers									$ 2,489	$ 2,559	$ 2,065