Fair Value Measurements 1 (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013		Mar. 31, 2012
Assets:
Interest rate derivatives	$ 19		$ 27
Fair Value, Measurements, Recurring [Member]
Assets:
Foreign exchange derivatives	1	[1]	2	[1]
Interest rate derivatives	19	[1]	27	[1]
Total assets	1,300		1,403
Liabilities:
Foreign exchange derivatives	0	[1]	4	[1]
Total liabilities	0		4
Fair Value, Measurements, Recurring [Member] | Money Market Funds [Member]
Assets:
Money market funds	1,280	[2]	1,374	[3]
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets:
Total assets	1,280		1,374
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Money Market Funds [Member]
Assets:
Money market funds	1,280		1,374
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets:
Foreign exchange derivatives	1	[1]	2	[1]
Interest rate derivatives	19	[1]	27	[1]
Total assets	20		29
Liabilities:
Foreign exchange derivatives	0	[1]	4	[1]
Total liabilities	$ 0		$ 4

[1] See Note 9, “Derivatives” for additional information. Interest rate derivatives fair value excludes accrued interest.

[2] At March 31, 2013, the Company had approximately $1,230 million and $50 million of investments in money market funds classified as “Cash and cash equivalents” and “Other noncurrent assets, net” for restricted cash amounts, respectively, in its Consolidated Balance Sheet.

[3] At March 31, 2012, the Company had approximately $1,324 million and $50 million of investments in money market funds classified as “Cash and cash equivalents” and “Other noncurrent assets, net” for restricted cash amounts, respectively, in its Consolidated Balance Sheet.