Securitizations and Variable Interest Entities - Schedule of Expected Losses (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Variable Interest Entity [Line Items]
Carrying Value	$ 312	$ 131
Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Carrying Value	312	131
Total Exposure	312	131
Rated notes | Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Carrying Value	229	98
Total Exposure	229	98
Certificates and other assets | Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Carrying Value	83	33
Total Exposure	$ 83	$ 33