Commitments and Contingent Liabilities (Litigation Reserve and Expense) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Sep. 30, 2013	Jun. 30, 2013	Sep. 30, 2012	Jun. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Loss Contingencies [Line Items]
Charges incurred	$ 35		$ 44		$ 50	$ 60
Payments made					(20)	(438)
Average Wholesale Price Litigation [Member]
Loss Contingencies [Line Items]
AWP litigation reserve at beginning of period		42		453	42	453
Charges incurred	35	15	44	16	50	60
Payments made					(20)	(438)
AWP litigation reserve at end of period	$ 72		$ 75		$ 72	$ 75