Balance Sheet Components Pension and Other Postretirement Benefits (Details) - Pension Plan [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 4	$ 4	$ 12	$ 12
Interest cost	8	8	24	25
Expected return on plan assets	(11)	(10)	(33)	(30)
Amortization of net actuarial loss	4	3	12	8
Net periodic benefit cost	$ 5	$ 5	$ 15	$ 15