Debt and Financing Activities Debt and Financing Activities (Narrative) (Details)			9 Months Ended		9 Months Ended			9 Months Ended			9 Months Ended		9 Months Ended		12 Months Ended
	Dec. 31, 2014 USD ($)	Mar. 31, 2014 USD ($)	Dec. 31, 2014 Accounts Receivable Factoring Facility Celesio [Member] USD ($)	Mar. 31, 2014 Accounts Receivable Factoring Facility Celesio [Member] USD ($)	Dec. 31, 2014 Revolving Credit Facility USD ($)	Dec. 31, 2013 Revolving Credit Facility USD ($)	Mar. 31, 2014 Revolving Credit Facility USD ($)	Dec. 31, 2014 Revolving Credit Facility Celesio [Member] USD ($)	Dec. 31, 2014 Revolving Credit Facility Celesio [Member] EUR (€)	Mar. 31, 2014 Revolving Credit Facility Celesio [Member] USD ($)	Dec. 31, 2014 Bilateral Lines of Credit Celesio [Member] USD ($)	Mar. 31, 2014 Bilateral Lines of Credit Celesio [Member] USD ($)	Dec. 31, 2014 Accounts Receivable Sales Facility [Member] USD ($)	Dec. 31, 2013 Accounts Receivable Sales Facility [Member] USD ($)	Mar. 31, 2014 Accounts Receivable Sales Facility [Member] USD ($)	Dec. 31, 2014 Corporate Bonds Celesio [Member] USD ($)	Mar. 31, 2014 Corporate Bonds Celesio [Member] USD ($)	Dec. 31, 2014 4.00% Bonds Celesio [Member] USD ($)	Mar. 31, 2014 4.00% Bonds Celesio [Member] USD ($)	Dec. 31, 2014 4.50% Bonds Celesio [Member] USD ($)	Mar. 31, 2014 4.50% Bonds Celesio [Member] USD ($)
Debt [Line Items]
Debt stated interest rate																		4.00%	4.00%	4.50%	4.50%
Long-term debt	$ 10,000,000,000	$ 10,400,000,000														$ 1,079,000,000	$ 1,244,000,000	$ 440,000,000	$ 507,000,000	$ 639,000,000	$ 737,000,000
Credit facility capacity			283,000,000		1,300,000,000				500,000,000		1,800,000,000		1,350,000,000
Credit facility expiration date			Jan. 31, 2016		Sep. 23, 2016			Feb. 28, 2018					Nov. 15, 2016
Proceeds from lines of credit			2,200,000,000		0	0		0			259,000,000		0	150,000,000
Repayments of lines of credit			2,154,000,000								196,000,000			150,000,000
Credit facility interest rate description					bear interest based upon either the London Interbank Offered Rate or a prime rate
Borrowings outstanding			246,000,000	246,000,000	0		0	0		0	225,000,000	188,000,000	0		0
Related accounts receivable outstanding			$ 246,000,000	$ 246,000,000									$ 0		$ 0
Credit facility covenant compliance													we were in compliance with all covenants		we were in compliance with all covenants