Employment Benefit Plans (Details) (USD $) In Millions, unless otherwise specified	0 Months Ended	3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended
	Jan. 31, 2012	Jun. 30, 2012 Pension Plans, Defined Benefit	Jun. 30, 2011 Pension Plans, Defined Benefit	Jun. 30, 2012 Pension Plans, Defined Benefit	Jun. 30, 2011 Pension Plans, Defined Benefit	Jun. 30, 2012 Other Postretirement Benefit Plans, Defined Benefit	Jun. 30, 2011 Other Postretirement Benefit Plans, Defined Benefit	Jun. 30, 2012 Other Postretirement Benefit Plans, Defined Benefit	Jun. 30, 2011 Other Postretirement Benefit Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Service cost		$ 9	$ 8	$ 19	$ 16	$ 1	$ 1	$ 1	$ 1
Interest cost		25	25	50	51	3	3	6	7
Expected return on plan assets		(29)	(30)	(59)	(60)
Amortization of net loss		2	0	5	0			1	0
Net cost recognized		7	3	15	7	4	4	8	8
Discretionary contribution by Company	$ 36