Employee Benefits, Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Pension benefits qualified [Member]
Components of net periodic benefit cost [Abstract]
Service cost	$ 1	$ 0	$ 1	$ 0
Interest cost	107	117	214	233
Expected return on plan assets	(161)	(158)	(322)	(315)
Amortization of net actuarial loss (gain)	27	23	54	46
Amortization of prior service credit	0	0	0	0
Settlement loss	0	0	0	0
Net periodic benefit cost (income)	(26)	(18)	(53)	(36)
Pension benefits nonqualified [Member]
Components of net periodic benefit cost [Abstract]
Service cost	0	0	0	0
Interest cost	7	8	13	14
Expected return on plan assets	0	0	0	0
Amortization of net actuarial loss (gain)	4	2	9	5
Amortization of prior service credit	0	0	0	0
Settlement loss	0	2	13	2
Net periodic benefit cost (income)	11	12	35	21
Other benefits [Member]
Components of net periodic benefit cost [Abstract]
Service cost	2	2	4	4
Interest cost	10	9	21	20
Expected return on plan assets	(9)	(9)	(18)	(18)
Amortization of net actuarial loss (gain)	(1)	(7)	(2)	(14)
Amortization of prior service credit	0	0	(1)	(1)
Settlement loss	0	0	0	0
Net periodic benefit cost (income)	$ 2	$ (5)	$ 4	$ (9)