Employee Benefit Plans (Quarterly Info) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Pension Benefits [Member]
Components of net periodic benefit cost (credit):
Service cost	$ 7	$ 8
Interest cost	7	7
Expected return on plan assets	(11)	(11)
Amortization of net actuarial loss	3	4
Net periodic benefit cost (credit)	6	8
Other Postretirement Benefits [Member]
Components of net periodic benefit cost (credit):
Interest cost	1	1
Expected return on plan assets	(2)	(2)
Reclassification to regulatory liability	0	1
Net periodic benefit cost (credit)	$ (1)	$ 0