Segment Information Segment Information (Asset Management and Service Fees) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Asset management and service fees	$ 1,033	$ 1,016
Asset-based management fees
Asset management and service fees	875	843
Performance-based incentive fees
Asset management and service fees	14	35
Other fees
Asset management and service fees	$ 144	$ 138