Summary of Significant Accounting Policies - Narrative (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024	Dec. 31, 2024
Debt and Equity Securities, FV-NI [Line Items]
Weighted average number of contingently issuable shares (shares)	4,700	4,700
Incremental common shares attributable to dilutive effect of conversion of preferred stock (in shares)	26	26	26	26
Investment in securities, trading, at fair value	$ 76,992		$ 76,992		$ 78,728
Securities received as collateral	63,900		63,900		56,300
Fair value of securities received as collateral that can be resold or repledged	61,700		61,700		49,000
Acquired property	1,800		1,800		1,700
Non-mortgage-related securities
Debt and Equity Securities, FV-NI [Line Items]
Investment in securities, trading, at fair value	75,807		75,807		77,630
Non-mortgage-related securities | Pledged as collateral
Debt and Equity Securities, FV-NI [Line Items]
Investment in securities, trading, at fair value	$ 9,700		$ 9,700		$ 8,900