Benefit Plans (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014 plans	Jun. 30, 2013	Jun. 30, 2014 plans	Jun. 30, 2013
Pension Benefits
General Discussion of Pension Plan
Number of defined benefit plans sponsored (plans)	4		4
Pension Contributions
Employer contributions to employee retirement plan			$ 30
Components of Net Periodic Benefit Expense and Other Postretirement Expense (Income):
Service cost	13	6	26	14
Interest cost	8	6	17	13
Expected return on plan assets	(7)	(6)	(15)	(12)
Amortization of prior service cost (credit)	1	0	1	0
Recognized net actuarial loss	3	6	7	13
Net Periodic Benefit Expense (Income)	18	12	36	28
Other Postretirement Benefits
Components of Net Periodic Benefit Expense and Other Postretirement Expense (Income):
Service cost	1	2	2	3
Interest cost	0	0	1	1
Amortization of prior service cost (credit)	(8)	(10)	(17)	(19)
Recognized net actuarial loss	2	3	3	5
Net Periodic Benefit Expense (Income)	$ (5)	$ (5)	$ (11)	$ (10)
Funded Qualified Employee Retirement Plan
General Discussion of Pension Plan
Number of defined benefit plans sponsored (plans)	1		1
Unfunded Nonqualified Executive Plan
General Discussion of Pension Plan
Number of defined benefit plans sponsored (plans)	3		3