Balance Sheet Components Pension and Other Postretirement Benefits (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 3	$ 3
Interest cost	8	7
Expected return on plan assets	(10)	(10)
Amortization of net actuarial loss	4	2
Net periodic benefit cost	5	2
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	1
Interest cost	1	1
Expected return on plan assets	0	0
Amortization of net actuarial loss	0	0
Net periodic benefit cost	2	2
Non Qualified Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0
Interest cost	1	1
Expected return on plan assets	0	0
Amortization of net actuarial loss	0	0
Net periodic benefit cost	$ 1	$ 1