Employee Benefits Schedule of Net Benefit Costs (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Other Postretirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 2	$ 2	$ 2
Interest cost on benefit obligation	4	3	3
Expected return on plan assets	(2)	(1)	(1)
Amortization of prior service cost	1	1	1
Amortization of net actuarial loss	1	1	1
Net periodic benefit cost	6	6	6
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	15	17	14
Interest cost on benefit obligation	34	30	31
Expected return on plan assets	(39)	(40)	(41)
Amortization of prior service cost	0	0	0
Amortization of net actuarial loss	17	24	17
Net periodic benefit cost	27	31	21
Non Qualified Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0	0
Interest cost on benefit obligation	1	1	1
Expected return on plan assets	0	0	0
Amortization of prior service cost	0	0	0
Amortization of net actuarial loss	1	1	1
Net periodic benefit cost	$ 2	$ 2	$ 2