Segment Information (Net Revenue By Geographic Area) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2012
Revenue from External Customer [Line Items]
Net revenue	$ 1,123	$ 808	$ 695	$ 949	$ 1,209	$ 922	$ 711	$ 955	$ 3,575	$ 3,797	$ 4,143
North America [Member]
Revenue from External Customer [Line Items]
Net revenue from unaffiliated customers									1,510	1,701	1,991
International [Member]
Revenue from External Customer [Line Items]
Net revenue from unaffiliated customers									$ 2,065	$ 2,096	$ 2,152