Goodwill And Intangible Assets, Net (Information Regarding Intangible Assets) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Jun. 30, 2013	Mar. 31, 2013
Intangible assets
Gross Carrying Amount	$ 3,320	$ 3,347
Accumulated Amortization	(1,124)	(1,077)
Net Carrying Amount	2,196	2,270
Customer lists [Member]
Intangible assets
Weighted Average Remaining Amortization Period (years)	7 years
Gross Carrying Amount	1,776	1,761
Accumulated Amortization	(710)	(672)
Net Carrying Amount	1,066	1,089
Service agreements [Member]
Intangible assets
Weighted Average Remaining Amortization Period (years)	17 years
Gross Carrying Amount	1,008	1,018
Accumulated Amortization	(129)	(114)
Net Carrying Amount	879	904
Trademarks and trade names [Member]
Intangible assets
Weighted Average Remaining Amortization Period (years)	16 years
Gross Carrying Amount	202	208
Accumulated Amortization	(47)	(46)
Net Carrying Amount	155	162
Technology [Member]
Intangible assets
Weighted Average Remaining Amortization Period (years)	4 years
Gross Carrying Amount	248	271
Accumulated Amortization	(201)	(207)
Net Carrying Amount	47	64
Other [Member]
Intangible assets
Weighted Average Remaining Amortization Period (years)	6 years
Gross Carrying Amount	86	89
Accumulated Amortization	(37)	(38)
Net Carrying Amount	$ 49	$ 51