Consolidations and Transfers of Financial Assets - Unconsolidated VIEs (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Variable Interest Entities [Line Items]
Trading, at fair value	$ 88,206	$ 136,542
Other assets	10,855	15,201
Other liabilities	(14,432)	(15,035)
Assets	4,229,166	3,985,749
Unpaid principal balance of mortgage loans	3,899,025	3,589,868
Multifamily
Variable Interest Entities [Line Items]
Unpaid principal balance of mortgage loans	403,452	373,722
Multifamily | Not Primary Beneficiary
Variable Interest Entities [Line Items]
Unpaid principal balance of mortgage loans	403,500
Fannie Mae Securities | Not Primary Beneficiary
Variable Interest Entities [Line Items]
Trading, at fair value	984	1,611
Available-for-sale securities	495	1,168
Non-Fannie Mae Securities | Not Primary Beneficiary
Variable Interest Entities [Line Items]
Trading, at fair value	3,030	3,608
Available-for-sale securities	200	318
Mortgage-related securities | Not Primary Beneficiary
Variable Interest Entities [Line Items]
Trading, at fair value	4,014	5,219
Available-for-sale securities	695	1,486
Other assets	35	41
Other liabilities	(41)	(67)
Net carrying amount	4,703	6,679
Maximum exposure to loss	220,000	146,000
Assets	250,000	180,000
Partnership Interest | Not Primary Beneficiary
Variable Interest Entities [Line Items]
Net carrying amount	288	121
Maximum exposure to loss	292	126
Assets	3,700	2,600
Debt Securities | Not Primary Beneficiary
Variable Interest Entities [Line Items]
Maximum exposure to loss	10,400	11,400
Assets	$ 10,400	$ 11,400