Balance Sheet Components Pension and Other Postretirement Benefits (Details) - Pension Plan [Member] - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 4	$ 4	$ 8	$ 8
Interest cost	9	8	17	16
Expected return on plan assets	(10)	(10)	(20)	(20)
Amortization of net actuarial loss	3	4	6	8
Net periodic benefit cost	$ 6	$ 6	$ 11	$ 12