Balance Sheet Components Pension and Other Postretirement Benefits (Details) - Pension Plan [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 4	$ 5	$ 12	$ 15
Interest cost	8	8	25	24
Expected return on plan assets	(10)	(10)	(30)	(31)
Amortization of net actuarial loss	3	4	8	12
Net periodic benefit cost	$ 5	$ 7	$ 15	$ 20