Balance Sheet Components Pension and Other Postretirement Benefits (Details) - Pension Plan [Member] - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 5	$ 4
Interest cost	7	8
Expected return on plan assets	(11)	(11)
Amortization of net actuarial loss	5	4
Net periodic benefit cost	$ 6	$ 5