Employee Benefit Plans (Details 1) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Pension Benefits [Member]
Component of periodic benefit cost
Service cost	$ 0	$ 26
Interest cost	60	63
Expected return on plan assets	(79)	(78)
Amortization of prior service credit	0	(2)
Amortization of actuarial loss	14	53
Net periodic benefit cost	(5)	62
Other Postretirement Benefits [Member]
Component of periodic benefit cost
Service cost	0	1
Interest cost	3	5
Expected return on plan assets	(3)	(3)
Amortization of prior service credit	(2)	0
Amortization of actuarial loss	0	0
Net periodic benefit cost	$ (2)	$ 3