Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Cash flows used in operating activities:
Net cash provided by (used in) operating activities	$ (6,420)	$ (114)
Cash flows provided by investing activities:
Purchases of trading securities held for investment	(2,021)	(226)
Proceeds from maturities and paydowns of trading securities held for investment	659	756
Proceeds from sales of trading securities held for investment	781	413
Purchases of available-for-sale securities	0	(9)
Proceeds from maturities and paydowns of available-for-sale securities	2,689	2,929
Proceeds from sales of available-for-sale securities	270	401
Purchases of loans held for investment	(60,504)	(38,276)
Net change in restricted cash	10,688	(5,124)
Advances to lenders	(38,471)	(26,131)
Proceeds from disposition of acquired property and preforeclosure sales	13,057	10,195
Net change in federal funds sold and securities purchased under agreements to resell or similar agreements	(46,850)	31,000
Other, net	7	(208)
Net cash provided by investing activities	100,120	157,530
Cash flows used in financing activities:
Payments of cash dividends on senior preferred stock to Treasury	(4,224)	(2,819)
Proceeds from senior preferred stock purchase agreement with Treasury	0	4,571
Other, net	216	(8)
Net cash used in financing activities	(91,404)	(152,906)
Net increase (decrease) in cash and cash equivalents	2,296	4,510
Cash and cash equivalents at beginning of period	21,117	17,539
Cash and cash equivalents at end of period	23,413	22,049
Cash paid during the period for:
Cash paid during the period for interest	27,824	30,590
Fannie Mae [Member]
Cash flows provided by investing activities:
Proceeds from repayments of loans held for investment	18,470	6,856
Cash flows used in financing activities:
Proceeds from the issuance of debt	155,561	167,848
Payments to redeem debt	(141,422)	(214,701)
Consolidated Trusts [Member]
Cash flows provided by investing activities:
Proceeds from repayments of loans held for investment	201,345	174,954
Cash flows used in financing activities:
Proceeds from the issuance of debt	122,408	80,933
Payments to redeem debt	$ (223,943)	$ (188,730)