Variable Interest Entities - Supplemental Information about Loans Held as Assets and Long-Term Debt Associated with Consolidated Variable Interest Entities (Detail) - Variable Interest Entity [Member] - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Variable Interest Entities [Line Items]
Long-term Debt, Fair Value	$ 4,056	$ 4,324
Loans, Unpaid principal balance	2,363	2,546
Long-term debt, Unpaid principal balance	$ 3,579	$ 3,769