Other Revenues and Other Expenses (Other Revenues - Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Distribution service
Revenue from Contract with Customer, Including Assessed Tax	$ 76	$ 85	$ 157	$ 167