Employee Benefit Plans (Schedule of Changes, Net of Tax, in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income (Loss)) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011
Actuarial gain (loss) arising during the period	$ (176)
Amortization of net actuarial gain (loss)	42
Amortization of prior service (cost) credit	3
Amortization of transition obligation	4
Total recognized in other comprehensive income (loss)	(127)
Postretirement Benefit Plan
Actuarial gain (loss) arising during the period	2
Amortization of net actuarial gain (loss)	1
Amortization of prior service (cost) credit	1
Amortization of transition obligation	4
Total recognized in other comprehensive income (loss)	8
Qualified Plans [Member] | Pension Plans, Defined Benefit [Member]
Actuarial gain (loss) arising during the period	(149)
Amortization of net actuarial gain (loss)	34
Amortization of prior service (cost) credit	4
Amortization of transition obligation	0
Total recognized in other comprehensive income (loss)	(111)
Non Qualified Plans [Member] | Pension Plans, Defined Benefit [Member]
Actuarial gain (loss) arising during the period	(29)
Amortization of net actuarial gain (loss)	7
Amortization of prior service (cost) credit	(2)
Amortization of transition obligation	0
Total recognized in other comprehensive income (loss)	$ (24)