Financial Instruments and Commodity Contracts (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014		Mar. 31, 2014
Assets
Derivative Assets, Current	$ 79		$ 51
Derivative Assets, Noncurrent	2	[1]	4	[1]
Liabilities
Derivative Liabilities, Current	(96)		(60)
Derivative Liabilities, Noncurrent	(14)	[1]	(19)	[1]
Net Fair Value Assets/Liabilities	(29)		(24)
Designated as hedging instrument [Member]
Assets
Derivative Assets, Current	28		22
Derivative Assets, Noncurrent	2	[1]	4	[1]
Liabilities
Derivative Liabilities, Current	(26)		(22)
Derivative Liabilities, Noncurrent	(5)	[1]	(6)	[1]
Net Fair Value Assets/Liabilities	(1)		(2)
Designated as hedging instrument [Member] | Cash flow hedges [Member] | Commodity Contract [Member]
Assets
Derivative Assets, Current	12		4
Derivative Assets, Noncurrent	0	[1]	0	[1]
Liabilities
Derivative Liabilities, Current	(10)		(7)
Derivative Liabilities, Noncurrent	0	[1]	0	[1]
Net Fair Value Assets/Liabilities	2		(3)
Designated as hedging instrument [Member] | Cash flow hedges [Member] | Currency Exchange Contract [Member]
Assets
Derivative Assets, Current	12		15
Derivative Assets, Noncurrent	2	[1]	4	[1]
Liabilities
Derivative Liabilities, Current	(14)		(13)
Derivative Liabilities, Noncurrent	(5)	[1]	(6)	[1]
Net Fair Value Assets/Liabilities	(5)		0
Designated as hedging instrument [Member] | Cash flow hedges [Member] | Energy Related Derivative [Member]
Assets
Derivative Assets, Current	1		3
Derivative Assets, Noncurrent	0	[1]	0	[1]
Liabilities
Derivative Liabilities, Current	(1)		0
Derivative Liabilities, Noncurrent	0	[1]	0	[1]
Net Fair Value Assets/Liabilities	0		3
Designated as hedging instrument [Member] | Cash flow hedges [Member] | Interest Rate Swap [Member]
Assets
Derivative Assets, Current	0
Derivative Assets, Noncurrent	0	[1]
Liabilities
Derivative Liabilities, Current	(1)
Derivative Liabilities, Noncurrent	0	[1]
Net Fair Value Assets/Liabilities	(1)
Designated as hedging instrument [Member] | Net investment hedges [Member] | Currency Exchange Contract [Member]
Assets
Derivative Assets, Current			0
Derivative Assets, Noncurrent			0	[1]
Liabilities
Derivative Liabilities, Current			(1)
Derivative Liabilities, Noncurrent			0	[1]
Net Fair Value Assets/Liabilities			(1)
Designated as hedging instrument [Member] | Net investment hedges [Member] | Currency exchange contracts [Member]
Assets
Derivative Assets, Current	3
Derivative Assets, Noncurrent	0	[1]
Liabilities
Derivative Liabilities, Current	0
Derivative Liabilities, Noncurrent	0	[1]
Net Fair Value Assets/Liabilities	3
Designated as hedging instrument [Member] | Fair value hedging [Member] | Commodity Contract [Member]
Assets
Derivative Assets, Current			0
Derivative Assets, Noncurrent			0	[1]
Liabilities
Derivative Liabilities, Current			(1)
Derivative Liabilities, Noncurrent			0	[1]
Net Fair Value Assets/Liabilities			(1)
Not designated as hedging instrument [Member]
Assets
Derivative Assets, Current	51		29
Derivative Assets, Noncurrent	0	[1]	0	[1]
Liabilities
Derivative Liabilities, Current	(70)		(38)
Derivative Liabilities, Noncurrent	(9)	[1]	(13)	[1]
Net Fair Value Assets/Liabilities	(28)		(22)
Not designated as hedging instrument [Member] | Commodity Contract [Member]
Assets
Derivative Assets, Current	28		19
Derivative Assets, Noncurrent	0	[1]	0	[1]
Liabilities
Derivative Liabilities, Current	(34)		(28)
Derivative Liabilities, Noncurrent	0	[1]	0	[1]
Net Fair Value Assets/Liabilities	(6)		(9)
Not designated as hedging instrument [Member] | Currency Exchange Contract [Member]
Assets
Derivative Assets, Current	23		9
Derivative Assets, Noncurrent	0	[1]	0	[1]
Liabilities
Derivative Liabilities, Current	(30)		(3)
Derivative Liabilities, Noncurrent	0	[1]	0	[1]
Net Fair Value Assets/Liabilities	(7)		6
Not designated as hedging instrument [Member] | Energy Related Derivative [Member]
Assets
Derivative Assets, Current	0		1
Derivative Assets, Noncurrent	0	[1]	0	[1]
Liabilities
Derivative Liabilities, Current	(6)		(7)
Derivative Liabilities, Noncurrent	(9)	[1]	(13)	[1]
Net Fair Value Assets/Liabilities	$ (15)		$ (19)

[1] The noncurrent portions of derivative assets and liabilities are included in “Other long-term assets-third parties” and in “Other long-term liabilities” respectively, in the accompanying condensed consolidated balance sheets