Supplementary Consolidated Financial Statement Schedule Valuation And Qualifying Accounts (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Mar. 31, 2012		Mar. 31, 2011		Mar. 31, 2010
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	$ 140	[1]	$ 155	[1]	$ 164
Charged to Costs and Expenses	35		18		23
Charged to Other Accounts	0	[2]	3	[2]	17	[2]
Deductions From Allowance Accounts	(50)	[3]	(36)	[3]	(49)	[3]
Balance at End of Year	125	[1]	140	[1]	155	[1]
Allowance For Doubtful Accounts [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	124	[1]	131	[1]	152
Charged to Costs and Expenses	30		18		17
Charged to Other Accounts	0	[2]	5	[2]	7	[2]
Deductions From Allowance Accounts	(43)	[3]	(30)	[3]	(45)	[3]
Balance at End of Year	111	[1]	124	[1]	131	[1]
Other Allowances [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	16	[1]	24	[1]	12
Charged to Costs and Expenses	5		0		6
Charged to Other Accounts	0	[2]	(2)	[2]	10	[2]
Deductions From Allowance Accounts	(7)	[3]	(6)	[3]	(4)	[3]
Balance at End of Year	14	[1]	16	[1]	24	[1]
Written Off [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Deductions From Allowance Accounts	(44)		(36)		(49)
Credited To Other Accounts [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Deductions From Allowance Accounts	(6)		0		0
Deductions [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Deductions From Allowance Accounts	(50)		(36)		(49)
Amounts Shown As Deductions From Current And Non-Current Receivables [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at End of Year	$ 125		$ 140		$ 155

[1] Amounts shown as deductions from current and non - current receivables $ 125 $ 140 $ 155

[2] Primarily represents reclassifications from other balance sheet accounts.

[3] Deductions: Written off $ (44 ) $ (36 ) $ (49 ) Credited to other accounts (6 ) 0 0 Total $ (50 ) $ (36 ) $ (49 )