Balance Sheet Components Pension and Other Postretirement Benefits (Details) - Pension Plan [Member] - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 4	$ 5	$ 8	$ 10
Interest cost	9	8	17	16
Expected return on plan assets	(10)	(11)	(20)	(21)
Amortization of net actuarial loss	2	4	5	8
Net periodic benefit cost	$ 5	$ 6	$ 10	$ 13