Balance Sheet Components Pension and Other Postretirement Benefits (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 3	$ 3	$ 9	$ 9
Interest cost	8	7	24	21
Expected return on plan assets	(10)	(10)	(30)	(30)
Amortization of prior service cost	0	0	0	0
Amortization of net actuarial loss	4	2	12	6
Net periodic benefit cost	5	2	15	6
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	1	1	2
Interest cost	1	1	3	3
Expected return on plan assets	0	0	0	0
Amortization of prior service cost	1	0	1	0
Amortization of net actuarial loss	0	0	0	0
Net periodic benefit cost	2	2	5	5
Non Qualified Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0	0	0
Interest cost	0	1	1	2
Expected return on plan assets	0	0	0	0
Amortization of prior service cost	0	0	0	0
Amortization of net actuarial loss	0	0	0	0
Net periodic benefit cost	$ 0	$ 1	$ 1	$ 2