Fair Value Measurements - Quantitative Information about Nonrecurring Level 3 Fair Value Financial Instruments and the Fair Value Measurements (Details) - Nonrecurring - Level 3 $ in Millions	Sep. 30, 2022 USD ($) loss_severity_discount_per_loan	Dec. 31, 2021 USD ($) loss_severity_discount_per_loan
Commercial loans
Fair Value Inputs, Assets, Quantitative Information
Commercial loans | $		$ 18
Residential first mortgage loans
Fair Value Inputs, Assets, Quantitative Information
Loans held-for-investment | $	$ 54	$ 36
Residential first mortgage loans | Lower range | Loss severity discount
Fair Value Inputs, Assets, Quantitative Information
Loans held for investment, fair value input (in percentage)	0	0
Residential first mortgage loans | Upper range | Loss severity discount
Fair Value Inputs, Assets, Quantitative Information
Loans held for investment, fair value input (in percentage)	1	1
Residential first mortgage loans | Weighted average | Loss severity discount
Fair Value Inputs, Assets, Quantitative Information
Loans held for investment, fair value input (in percentage)	0.043	0.127
Repossessed assets
Fair Value Inputs, Assets, Quantitative Information
Loans held-for-investment | $	$ 6	$ 6
Repossessed assets | Lower range | Loss severity discount
Fair Value Inputs, Assets, Quantitative Information
Repossessed assets, fair value input (in percentage)	0	0
Repossessed assets | Upper range | Loss severity discount
Fair Value Inputs, Assets, Quantitative Information
Repossessed assets, fair value input (in percentage)	0.756	0.963
Repossessed assets | Weighted average | Loss severity discount
Fair Value Inputs, Assets, Quantitative Information
Repossessed assets, fair value input (in percentage)	0.226	0.198