Employee Benefit Plans (Retirement Plan Expense) (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended		12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2010
Defined Benefit Plan Disclosure [Line Items]
Remeasurement charge			$ 34
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost (benefits earned during the period)	44	36	71	71	58
Interest cost	61	65	130	120	119
Expected return on plan assets	(75)	(70)	(141)	(132)	(117)
Settlement charges	68	0
Remeasurement charge			30
Amortization of actuarial loss	42	24	52	59	31
Other amortization	2	2	5	5	6
Net periodic defined benefit plan expense	142	57	147	123	97
Defined contribution plans	23	23	45	43	40
Total retirement plan expense	165	80	192	166	137
U.S. Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Settlement charges	53
Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost (benefits earned during the period)	4	3	7	8	9
Interest cost	6	6	12	13	16
Remeasurement charge			4
Amortization of actuarial loss					5
Other amortization			(2)	(1)	(1)
Net periodic defined benefit plan expense	10	9	21	20	29
Total retirement plan expense	$ 10	$ 9	$ 21	$ 20	$ 29