Financial Instruments (Schedule of the Fair Value of Derivative Instruments) (Details) (Fair Value, Measurements, Recurring [Member], Fair Value, Inputs, Level 2 [Member], USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Mar. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset Derivatives	$ 223	$ 253
Liability Derivatives	57	36
Designated as Hedging Instrument [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset Derivatives	94	110
Liability Derivatives	7	13
Not Designated as Hedging Instrument [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset Derivatives	129	143
Liability Derivatives	50	23
Other Assets [Member] | Interest Rate Swap [Member] | Designated as Hedging Instrument [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset Derivatives	63	66
Other Assets [Member] | Foreign Currency Contract [Member] | Not Designated as Hedging Instrument [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset Derivatives	34	43
Accounts and Notes Receivable [Member] | Foreign Currency Contract [Member] | Designated as Hedging Instrument [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset Derivatives	31	44
Accounts and Notes Receivable [Member] | Foreign Currency Contract [Member] | Not Designated as Hedging Instrument [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset Derivatives	95	100
Other Accrued Liabilities [Member] | Foreign Currency Contract [Member] | Designated as Hedging Instrument [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liability Derivatives	7	12
Other Accrued Liabilities [Member] | Foreign Currency Contract [Member] | Not Designated as Hedging Instrument [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liability Derivatives	48	21
Other Accrued Liabilities [Member] | Commodity Contract [Member] | Designated as Hedging Instrument [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liability Derivatives	0	1
Other Accrued Liabilities [Member] | Commodity Contract [Member] | Not Designated as Hedging Instrument [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liability Derivatives	$ 2	$ 2