Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Assets:
Restricted cash (includes $22,774 and $22,132, respectively, related to consolidated trusts)	$ 27,876	$ 28,150
Investments in securities:
Trading, at fair value (includes $3,363 and $747, respectively, pledged as collateral)	3,363	747
Available-for-sale, at fair value	3,723	4,843
Accrued interest receivable, net (includes $7,702 and $7,560, respectively, related to consolidated trusts)	8,256	8,133
Mortgage loans:
Total loans held for investment (includes $9,628 and $10,596, respectively, at fair value)	9,628	10,596
Liabilities:
Accrued interest payable (includes $8,751 and $8,598, respectively, related to consolidated trusts)	9,825	9,682
Other liabilities (includes $353 and $492, respectively, related to consolidated trusts)	$ 8,591	$ 9,479
Fannie Mae stockholders’ equity (deficit):
Senior preferred stock, 1,000,000 shares issued	1,000,000	1,000,000
Senior preferred stock, 1,000,000 shares outstanding	1,000,000	1,000,000
Preferred stock, 700,000,000 shares are authorized	700,000,000	700,000,000
Preferred stock, 555,374,922 shares issued	555,374,922	555,374,922
Preferred stock, 555,374,922 shares outstanding	555,374,922	555,374,922
Common stock, 1,308,762,703 shares issued	1,308,762,703	1,308,762,703
Common stock, 1,158,087,567 shares outstanding	1,158,087,567	1,158,087,567
Treasury stock, at cost, 150,675,136 shares	150,675,136	150,675,136
Consolidated Trusts [Member]
Assets:
Restricted cash (includes $22,774 and $22,132, respectively, related to consolidated trusts)	$ 22,774	$ 22,132
Investments in securities:
Accrued interest receivable, net (includes $7,702 and $7,560, respectively, related to consolidated trusts)	7,702	7,560
Liabilities:
Accrued interest payable (includes $8,751 and $8,598, respectively, related to consolidated trusts)	8,751	8,598
Debt (includes $8,491 and $9,582, respectively, of debt of Fannie Mae at fair value and $32,760 and $36,524, respectively, of debt of consolidated trusts, at fair value)	26,675	30,493
Other liabilities (includes $353 and $492, respectively, related to consolidated trusts)	353	492
Fannie Mae [Member]
Liabilities:
Debt (includes $8,491 and $9,582, respectively, of debt of Fannie Mae at fair value and $32,760 and $36,524, respectively, of debt of consolidated trusts, at fair value)	$ 7,558	$ 8,186