Debt and Financing Activities (Celesio Debt) (Narrative) (Details) € in Millions, £ in Millions	3 Months Ended		12 Months Ended
	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Mar. 31, 2014	Jun. 30, 2015 EUR (€)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 GBP (£)	Mar. 31, 2015 USD ($)
Line of Credit Facility [Line Items]
Long-term debt					$ 9,700,000,000		$ 9,700,000,000
Repayments of debt and capital lease obligations	$ 96,000,000	$ 228,000,000
Accounts receivable sales facility
Line of Credit Facility [Line Items]
Credit facility capacity					1,350,000,000
Line of credit facility, expiration date	Nov. 15, 2016
Proceeds from lines of credit	$ 0
Repayments of lines of credit		0
Line of credit facility, covenant compliance	we were in compliance with all covenants		we were in compliance with all covenants
Borrowings outstanding					0		0
Revolving credit facility
Line of Credit Facility [Line Items]
Credit facility capacity					1,300,000,000
Line of credit facility, expiration date	Sep. 23, 2016
Proceeds from lines of credit	$ 0	0
Line of credit facility, interest rate description	bear interest based upon either the London Interbank Offered Rate or a prime rate
Borrowings outstanding					0		0
Celesio | Bonds [Member]
Line of Credit Facility [Line Items]
Long-term debt						£ 60	89,000,000
Repayments of debt and capital lease obligations	$ 93,000,000
Celesio | Accounts receivable factoring facility
Line of Credit Facility [Line Items]
Credit facility capacity					179,000,000
Line of credit facility, expiration date	Jan. 31, 2016
Proceeds from lines of credit	$ 285,000,000	758,000,000
Repayments of lines of credit	295,000,000	746,000,000
Borrowings outstanding					132,000,000		135,000,000
Celesio | Revolving credit facility
Line of Credit Facility [Line Items]
Credit facility capacity					1,400,000,000
Proceeds from lines of credit	246,000,000	147,000,000
Repayments of lines of credit	$ 240,000,000	16,000,000
Borrowings outstanding					40,000,000		29,000,000
Celesio | Revolving credit facility | Revolving credit facility due february two thousand eighteen
Line of Credit Facility [Line Items]
Credit facility capacity | €				€ 500
Line of credit facility, expiration date	Feb. 28, 2018
Proceeds from lines of credit	$ 0	$ 0
Borrowings outstanding					$ 0		0
Four percent bonds due october eighteen two thousand sixteen | Celesio
Line of Credit Facility [Line Items]
Debt instrument, interest rate, stated percentage				4.00%	4.00%
Long-term debt					$ 402,000,000		388,000,000
Four percent bonds due october eighteen two thousand sixteen | Celesio | Bonds [Member]
Line of Credit Facility [Line Items]
Long-term debt					$ 984,000,000
Four point five percent bonds due april twenty six two thousand seventeen | Celesio
Line of Credit Facility [Line Items]
Debt instrument, interest rate, stated percentage				4.50%	4.50%
Long-term debt					$ 582,000,000		563,000,000
Four point five percent bonds due april twenty six two thousand seventeen | Celesio | Bonds [Member]
Line of Credit Facility [Line Items]
Long-term debt							$ 951,000,000