Variable Interest Entities - Variable Interests Held by Us and Our Maximum Exposure to Loss Rising From Our Involvements in Those VIEs (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Variable Interest Entity [Line Items]
Total Assets Held by Unconsolidated VIEs	$ 3,684	$ 4,611
Variable Interest Held Classified as Assets	1,071	2,257
Variable Interests Held Classified as Liabilities	309	229
Maximum Exposure to Loss	2,077	3,457
Structured note vehicles [Member]
Variable Interest Entity [Line Items]
Total Assets Held by Unconsolidated VIEs	1,524	3,033
Variable Interest Held Classified as Assets	510	1,803
Variable Interests Held Classified as Liabilities	9	20
Maximum Exposure to Loss	1,515	3,003
Limited partnership investments [Member]
Variable Interest Entity [Line Items]
Total Assets Held by Unconsolidated VIEs	2,160	1,578
Variable Interest Held Classified as Assets	561	454
Variable Interests Held Classified as Liabilities	300	209
Maximum Exposure to Loss	$ 562	$ 454