Carrying value as of the balance sheet date of short-term borrowings using unsecured obligations issued by banks, corporations and other borrowers to investors. The maturities of these money market securities generally do not exceed 270 days.

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Debt (Schedule Of Outstanding Debt) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Mar. 31, 2015
Debt Instrument [Line Items]
Commercial paper outstanding	$ 50		$ 0
Current portion of long-term debt	262		12
Short-term debt	312		12
Long-term debt, current and noncurrent	4,757		4,414
Long-term debt and capital lease obligations	4,495		4,402
5.875% Senior Debt Obligations Due 2033
Debt Instrument [Line Items]
Long-term debt, current and noncurrent	$ 297		297
Interest rate	5.875%
2.30% Senior Debt Obligations Due 2017
Debt Instrument [Line Items]
Long-term debt, current and noncurrent	$ 250		249
Interest rate	2.30%
4.80% Senior Debt Obligations Due 2021
Debt Instrument [Line Items]
Long-term debt, current and noncurrent	$ 498		497
Interest rate	4.80%
3.30% Senior Debt Obligations Due 2023
Debt Instrument [Line Items]
Long-term debt, current and noncurrent	$ 347		0
Interest rate	3.30%	3.30%
2.55% Senior Debt Obligations Due 2018
Debt Instrument [Line Items]
Long-term debt, current and noncurrent	$ 249		249
Interest rate	2.55%
4.05% Senior Debt Obligations Due 2023
Debt Instrument [Line Items]
Long-term debt, current and noncurrent	$ 248		248
Interest rate	4.05%
3.50% Senior Debt Obligations Due 2024
Debt Instrument [Line Items]
Long-term debt, current and noncurrent	$ 596		595
Interest rate	3.50%
2.35% Senior Debt Obligations Due 2019
Debt Instrument [Line Items]
Long-term debt, current and noncurrent	$ 299		298
Interest rate	2.35%
3.50% Senior Debt Obligations Due 2025
Debt Instrument [Line Items]
Long-term debt, current and noncurrent	$ 495		495
Interest rate	3.50%
3.75% Senior Debt Obligations Due 2026
Debt Instrument [Line Items]
Long-term debt, current and noncurrent	$ 596		595
Interest rate	3.75%			3.75%
2.35% Senior Debt Obligations Due 2020
Debt Instrument [Line Items]
Long-term debt, current and noncurrent	$ 497		496
Interest rate	2.35%				2.35%
Mortgage Due 2035
Debt Instrument [Line Items]
Long-term debt, current and noncurrent	$ 382		393
Interest rate	5.70%
Other Debt Instruments
Debt Instrument [Line Items]
Long-term debt, current and noncurrent	$ 3		$ 2