Consolidations and Transfers of Financial Assets - Unconsolidated VIEs (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Variable Interest Entities [Line Items]
Total Assets	$ 4,335,856	$ 4,349,731
Total unpaid principal balance of mortgage loans	4,098,616	4,110,196
Multifamily
Variable Interest Entities [Line Items]
Total unpaid principal balance of mortgage loans	511,891	490,358
Multifamily | Unconsolidated VIEs
Variable Interest Entities [Line Items]
Total unpaid principal balance of mortgage loans	511,900
Securitization and resecuritization trusts | Unconsolidated VIEs
Variable Interest Entities [Line Items]
Total Assets	404,895	203,841
Maximum Exposure to Loss	194,206	203,316
Net carrying amount	5,200	1,200
Credit risk transfer SPVs | Unconsolidated VIEs
Variable Interest Entities [Line Items]
Total Assets	24,490	23,222
Maximum Exposure to Loss	24,499	23,224
Limited partnerships, including low income housing tax credit ("LIHTC") investments
Variable Interest Entities [Line Items]
Net carrying amount	2,200	2,000
Limited partnerships, including low income housing tax credit ("LIHTC") investments | Unconsolidated VIEs
Variable Interest Entities [Line Items]
Total Assets	6,602	6,428
Maximum Exposure to Loss	727	669
Net carrying amount	$ 727	$ 669