Fair Value Measurements 1 (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013		Mar. 31, 2013
Assets
Interest rate derivatives	$ 14		$ 19
Fair Value, Measurements, Recurring [Member]
Assets
Foreign exchange derivatives	9	[1]	1	[1]
Interest rate derivatives	14	[1]	19	[1]
Total assets	1,026		1,300
Liabilities
Foreign exchange derivatives	7	[1]	0	[1]
Total liabilities	7		0
Fair Value, Measurements, Recurring [Member] | Money Market Funds [Member]
Assets
Money market funds	1,003	[2]	1,280	[3]
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets
Total assets	1,003		1,280
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Money Market Funds [Member]
Assets
Money market funds	1,003		1,280
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets
Foreign exchange derivatives	9	[1]	1	[1]
Interest rate derivatives	14	[1]	19	[1]
Total assets	23		20
Liabilities
Foreign exchange derivatives	7	[1]	0	[1]
Total liabilities	$ 7		$ 0

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

[2] At September 30, 2013, the Company had approximately $953 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 Condensed Consolidated Balance Sheet.

[3] 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 Condensed Consolidated Balance Sheet.