Commitments and Contingent Liabilities (Narrative (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended		1 Months Ended		3 Months Ended					9 Months Ended		3 Months Ended	9 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Nov. 30, 2012 Distribution Solutions [Member] Average Wholesale Price Litigation [Member] AHCCCS Penalties [Member]	Nov. 30, 2012 Distribution Solutions [Member] Average Wholesale Price Litigation [Member] AHCCCS Assessment [Member]	Dec. 31, 2012 Distribution Solutions [Member] Operating Expense [Member] Average Wholesale Price Litigation [Member]	Sep. 30, 2012 Distribution Solutions [Member] Operating Expense [Member] Average Wholesale Price Litigation [Member]	Jun. 30, 2012 Distribution Solutions [Member] Operating Expense [Member] Average Wholesale Price Litigation [Member]	Dec. 31, 2011 Distribution Solutions [Member] Operating Expense [Member] Average Wholesale Price Litigation [Member]	Sep. 30, 2011 Distribution Solutions [Member] Operating Expense [Member] Average Wholesale Price Litigation [Member]	Dec. 31, 2012 Distribution Solutions [Member] Operating Expense [Member] Average Wholesale Price Litigation [Member]	Dec. 31, 2011 Distribution Solutions [Member] Operating Expense [Member] Average Wholesale Price Litigation [Member]	Dec. 31, 2012 Distribution Solutions [Member] Operating Expense [Member] RAMQ [Member]	Dec. 31, 2012 Distribution Solutions [Member] Operating Expense [Member] RAMQ [Member]
Loss Contingencies [Line Items]
Loss Contingency, Damages Sought, Value					$ 112	$ 102
Litigation charges	$ 0	$ 27	$ 60	$ 145			$ 0	$ 44	$ 16	$ 27	$ 118	$ 60	$ 145	$ 40	$ 40