Other Revenues and Other Expenses (Other Revenues - Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Distribution service
Revenue from Contract with Customer, Including Assessed Tax	$ 83	$ 84	$ 240	$ 251