Benefit Plans (Summary of the components of net periodic benefit cost recognized for pension plans) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Qualified Pension Plan [Member}
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 31	$ 32	$ 96	$ 106
Interest cost	31	27	93	81
Estimated return on plan assets	(74)	(65)	(222)	(193)
Amortization and other	2	20	3	60
Net periodic benefit cost	(10)	14	(30)	54
Nonqualified Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	2	2	8	8
Interest cost	5	2	12	9
Estimated return on plan assets	0	0	0	0
Amortization and other	3	3	9	9
Net periodic benefit cost	$ 10	$ 7	$ 29	$ 26