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, 2021		Dec. 31, 2020		Mar. 31, 2020
Variable Interest Entity [Line Items]
Assets		$ 194,856	[1]	$ 196,434	[1]	$ 205,077
Liabilities	[1]	176,882		178,143
Limited Partnership Investments [Member]
Variable Interest Entity [Line Items]
Total Assets Held by Unconsolidated VIEs		4,713		4,266
Assets		676		629
Liabilities		330		285
Maximum Exposure to Loss		$ 676		$ 629

[1] Assets