Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017
Net cash provided by (used in) operating activities
Net cash provided by (used in) operating activities	$ (1,796.0)	$ 172.0
Cash flows provided by investing activities:
Proceeds from maturities and paydowns of trading securities held for investment	163.0	1,088.0
Proceeds from sales of trading securities held for investment	96.0	149.0
Proceeds from maturities and paydowns of available-for-sale securities	564.0	1,671.0
Proceeds from sales of available-for-sale securities	729.0	1,207.0
Purchases of loans held for investment	(135,913.0)	(142,565.0)
Advances to lenders	(83,643.0)	(89,348.0)
Proceeds from disposition of acquired property and preforeclosure sales	7,090.0	9,671.0
Net change in federal funds sold and securities purchased under agreements to resell or similar arrangements	(7,128.0)	6,675.0
Other, net	(56.0)	344.0
Net cash provided by investing activities	110,564.0	135,436.0
Cash flows used in financing activities:
Payments of cash dividends on senior preferred stock to Treasury	(5,397.0)	(11,367.0)
Proceeds from senior preferred stock purchase agreement with Treasury	3,687.0	0.0
Other, net	720.0	88.0
Net cash used in financing activities	(117,997.0)	(145,734.0)
Net decrease in cash, cash equivalents and restricted cash	(9,229.0)	(10,126.0)
Cash, cash equivalents and restricted cash at beginning of period	60,260.0	62,177.0
Cash, cash equivalents and restricted cash at end of period	51,031.0	52,051.0
Cash paid during the period for:
Interest	82,010.0	82,652.0
Income taxes	460.0	1,670.0
Fannie Mae [Member]
Cash flows provided by investing activities:
Proceeds from repayments of loans acquired as held for investment	11,651.0	17,721.0
Proceeds from sales of loans acquired as held for investment of Fannie Mae	10,637.0	5,399.0
Cash flows used in financing activities:
Proceeds from issuance of debt	636,466.0	776,380.0
Payments to redeem debt	(666,888.0)	(809,299.0)
Consolidated Trusts [Member]
Cash flows provided by investing activities:
Proceeds from repayments of loans acquired as held for investment	306,374.0	323,424.0
Cash flows used in financing activities:
Proceeds from issuance of debt	278,357.0	282,433.0
Payments to redeem debt	$ (364,942.0)	$ (383,969.0)

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