Employee Benefit Plans Employee Benefit Plans (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1	$ 2	$ 2	$ 3
Interest cost	14	13	28	27
Expected return on plan assets	(19)	(18)	(38)	(37)
Net amortization	7	12	15	24
Net periodic benefit cost	3	9	7	17
Other Postretirement Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	2	2	3	4
Interest cost	7	7	14	13
Expected return on plan assets	(7)	(8)	(15)	(15)
Net amortization	0	2	1	4
Net periodic benefit cost	$ 2	$ 3	$ 3	$ 6