Fair Value Measurements 1 (Details) (USD $) In Millions	Sep. 30, 2011	Mar. 31, 2011
Assets:
Interest rate derivatives	$ 30	$ 15
Fair Value, Measurements, Recurring [Member]
Assets:
Foreign exchange derivatives	22	7
Interest rate derivatives	30	15
Total Assets	1,026	2,210
Liabilities:
Foreign exchange derivatives not designated as hedges	12	1
Total Liabilities	12	1
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets:
Foreign exchange derivatives	0	0
Interest rate derivatives	0	0
Total Assets	795	2,009
Liabilities:
Foreign exchange derivatives not designated as hedges	0	0
Total Liabilities	0	0
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Money Market Funds [Member]
Assets:
Investments	795	2,009
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Marketable Securities [Member]
Assets:
Investments	0	0
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets:
Foreign exchange derivatives	22	7
Interest rate derivatives	30	15
Total Assets	231	201
Liabilities:
Foreign exchange derivatives not designated as hedges	12	1
Total Liabilities	12	1
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Money Market Funds [Member]
Assets:
Investments	0	0
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Marketable Securities [Member]
Assets:
Investments	179	179
Fair Value, Measurements, Recurring [Member] | Money Market Funds [Member]
Assets:
Investments	795	2,009
Fair Value, Measurements, Recurring [Member] | Marketable Securities [Member]
Assets:
Investments	$ 179	$ 179