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	Mar. 31, 2020	Dec. 31, 2019
Variable Interest Entity [Line Items]
Total Assets Held by Unconsolidated VIEs	$ 3,806	$ 3,684
Variable Interest Held Classified as Assets	1,101	1,071
Variable Interests Held Classified as Liabilities	449	309
Maximum Exposure to Loss	2,106	2,077
Structured note vehicles [Member]
Variable Interest Entity [Line Items]
Total Assets Held by Unconsolidated VIEs	1,657	1,524
Variable Interest Held Classified as Assets	510	510
Variable Interests Held Classified as Liabilities	142	9
Maximum Exposure to Loss	1,515	1,515
Limited partnership investments [Member]
Variable Interest Entity [Line Items]
Total Assets Held by Unconsolidated VIEs	2,149	2,160
Variable Interest Held Classified as Assets	591	561
Variable Interests Held Classified as Liabilities	307	300
Maximum Exposure to Loss	$ 591	$ 562