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		Sep. 30, 2021		Dec. 31, 2020		Sep. 30, 2020
Variable Interest Entity [Line Items]
Assets		$ 201,150	[1]	$ 196,434	[1]	$ 200,946
Liabilities	[1]	182,913		178,143
Limited Partnership Investments [Member]
Variable Interest Entity [Line Items]
Total Assets Held by Unconsolidated VIEs		4,759		4,266
Assets		737		629
Liabilities		405		285
Maximum Exposure to Loss		$ 737		$ 629

[1] Assets