Business Segment Reporting (Details) (USD $)	3 Months Ended				9 Months Ended
	Sep. 30, 2012		Sep. 30, 2011		Sep. 30, 2012		Sep. 30, 2011		Dec. 31, 2011
Segment Reporting Information [Line Items]
Interest income	$ 63,810,000		$ 71,121,000		$ 208,519,000		$ 202,045,000
Interest income related to consolidated trusts owned by third parties reclassified to guarantee fee income	0		0		0		0
Interest expense	(33,448,000)		(39,412,000)		(109,332,000)		(114,105,000)
Net interest income	30,362,000		31,709,000		99,187,000		87,940,000
Guarantee and commitment fees	6,401,000		6,148,000		18,395,000		18,855,000
Other income/(expense)	2,063,000		(61,553,000)		(23,034,000)		(67,098,000)
Non-interest income/(loss)	8,464,000		(55,405,000)		(4,639,000)		(48,243,000)
(Provision for)/release of loan losses	(137,000)		349,000		663,000		(1,092,000)
Release of (provision for) losses	43,000		452,000		(1,381,000)		3,321,000
Other non-interest expense	(7,791,000)		(8,002,000)		(23,418,000)		(24,740,000)
Non-interest expense	(7,748,000)		(7,550,000)		(24,799,000)		(21,419,000)
Income/(loss) before income taxes	30,941,000		(30,897,000)		70,412,000		17,186,000
Income tax (benefit)/expense	(8,294,000)		14,131,000		(17,319,000)		2,075,000
Net income/(loss)	22,647,000		(16,766,000)		53,093,000		19,261,000
Preferred stock dividends	(719,000)		(719,000)		(2,159,000)		(2,159,000)
Non-controlling interest - preferred stock dividends	(5,547,000)		(5,547,000)		(16,641,000)		(16,641,000)
Net income/(loss) attributable to common stockholders	16,381,000		(23,032,000)		34,293,000		461,000
Total assets at carrying value	12,502,481,000		11,430,507,000		12,502,481,000		11,430,507,000		11,883,508,000
Total on - and off - balance sheet program assets at principal balance	12,468,059,000		11,841,393,000		12,468,059,000		11,841,393,000
Farmer Mac I
Segment Reporting Information [Line Items]
Segment interest and dividend income operating	28,887,000	[1]	38,949,000	[1]	103,328,000	[1]	105,583,000	[1]
Interest income related to consolidated trusts owned by third parties reclassified to guarantee fee income	(190,000)		(782,000)		(1,463,000)		(2,495,000)
Segment interest expense	11,858,000	[2]	24,625,000	[2]	53,403,000	[2]	67,301,000	[2]
Segment net effective spread	16,839,000		13,542,000		48,462,000		35,787,000
Segment guarantee fee income	5,551,000		5,562,000		16,340,000		17,151,000
Other income/(expense)	519,000	[3]	236,000	[3]	1,470,000	[3]	2,459,000	[3]
Segment non interest income	6,070,000		5,798,000		17,810,000		19,610,000
(Provision for)/release of loan losses	(137,000)		349,000		663,000		(1,092,000)
Release of (provision for) losses	43,000		452,000		(1,381,000)		3,321,000
Other non-interest expense	(3,582,000)		(3,891,000)		(10,650,000)		(12,651,000)
Non-interest expense	(3,539,000)	[4]	(3,439,000)	[4]	(12,031,000)	[4]	(9,330,000)	[4]
Segment core earnings before income taxes	19,233,000		16,250,000		54,904,000		44,975,000
Income tax (benefit)/expense	(6,731,000)		(5,687,000)		(19,216,000)		(15,741,000)
Segment core earnings before preferred stock dividends and attibution of income to non-controlling interest - preferred stock dividends	12,502,000		10,563,000		35,688,000		29,234,000
Preferred stock dividends	0		0		0		0
Non-controlling interest - preferred stock dividends	0		0		0		0
Segment core earnings	12,502,000		10,563,000		35,688,000		29,234,000
Total assets at carrying value	5,046,716,000		4,790,409,000		5,046,716,000		4,790,409,000
Total on - and off - balance sheet program assets at principal balance	8,712,157,000		8,088,365,000		8,712,157,000		8,088,365,000
Farmer Mac II [Member]
Segment Reporting Information [Line Items]
Segment interest and dividend income operating	14,299,000	[1]	14,370,000	[1]	42,811,000	[1]	42,080,000	[1]
Interest income related to consolidated trusts owned by third parties reclassified to guarantee fee income	0		0		0		0
Segment interest expense	11,469,000	[2]	11,665,000	[2]	34,425,000	[2]	33,984,000	[2]
Segment net effective spread	2,830,000		2,705,000		8,386,000		8,096,000
Segment guarantee fee income	38,000		51,000		126,000		154,000
Other income/(expense)	251,000	[3]	26,000	[3]	525,000	[3]	131,000	[3]
Segment non interest income	289,000		77,000		651,000		285,000
(Provision for)/release of loan losses	0		0		0		0
Release of (provision for) losses	0		0		0		0
Other non-interest expense	(757,000)		(710,000)		(2,265,000)		(2,085,000)
Non-interest expense	(757,000)	[4]	(710,000)	[4]	(2,265,000)	[4]	(2,085,000)	[4]
Segment core earnings before income taxes	2,362,000		2,072,000		6,772,000		6,296,000
Income tax (benefit)/expense	(827,000)		(725,000)		(2,371,000)		(2,203,000)
Segment core earnings before preferred stock dividends and attibution of income to non-controlling interest - preferred stock dividends	1,535,000		1,347,000		4,401,000		4,093,000
Preferred stock dividends	0		0		0		0
Non-controlling interest - preferred stock dividends	0		0		0		0
Segment core earnings	1,535,000		1,347,000		4,401,000		4,093,000
Total assets at carrying value	1,640,940,000		1,483,750,000		1,640,940,000		1,483,750,000
Total on - and off - balance sheet program assets at principal balance	1,599,226,000		1,463,129,000		1,599,226,000		1,463,129,000
Rural Utilities
Segment Reporting Information [Line Items]
Segment interest and dividend income operating	15,401,000	[1]	13,135,000	[1]	48,223,000	[1]	39,928,000	[1]
Interest income related to consolidated trusts owned by third parties reclassified to guarantee fee income	0		0		0		0
Segment interest expense	12,292,000	[2]	10,089,000	[2]	38,931,000	[2]	30,793,000	[2]
Segment net effective spread	3,109,000		3,046,000		9,292,000		9,135,000
Segment guarantee fee income	1,002,000		1,317,000		3,392,000		4,045,000
Other income/(expense)	300,000	[3]	0	[3]	301,000	[3]	0	[3]
Segment non interest income	1,302,000		1,317,000		3,693,000		4,045,000
(Provision for)/release of loan losses	0		0		0		0
Release of (provision for) losses	0		0		0		0
Other non-interest expense	(1,368,000)		(1,319,000)		(4,135,000)		(3,698,000)
Non-interest expense	(1,368,000)	[4]	(1,319,000)	[4]	(4,135,000)	[4]	(3,698,000)	[4]
Segment core earnings before income taxes	3,043,000		3,044,000		8,850,000		9,482,000
Income tax (benefit)/expense	(1,065,000)		(1,065,000)		(3,097,000)		(3,319,000)
Segment core earnings before preferred stock dividends and attibution of income to non-controlling interest - preferred stock dividends	1,978,000		1,979,000		5,753,000		6,163,000
Preferred stock dividends	0		0		0		0
Non-controlling interest - preferred stock dividends	0		0		0		0
Segment core earnings	1,978,000		1,979,000		5,753,000		6,163,000
Total assets at carrying value	2,206,529,000		2,356,590,000		2,206,529,000		2,356,590,000
Total on - and off - balance sheet program assets at principal balance	2,156,676,000		2,289,899,000		2,156,676,000		2,289,899,000
Corporate
Segment Reporting Information [Line Items]
Segment interest and dividend income operating	6,437,000	[1]	6,880,000	[1]	18,693,000	[1]	21,100,000	[1]
Interest income related to consolidated trusts owned by third parties reclassified to guarantee fee income	0		0		0		0
Segment interest expense	1,959,000	[2]	3,408,000	[2]	4,736,000	[2]	10,722,000	[2]
Segment net effective spread	4,478,000		3,472,000		13,957,000		10,378,000
Segment guarantee fee income	0		0		0		0
Other income/(expense)	(699,000)	[3]	(946,000)	[3]	(1,939,000)	[3]	(1,686,000)	[3]
Segment non interest income	(699,000)		(946,000)		(1,939,000)		(1,686,000)
(Provision for)/release of loan losses	0		0		0		0
Release of (provision for) losses	0		0		0		0
Other non-interest expense	(2,084,000)		(2,082,000)		(6,368,000)		(6,306,000)
Non-interest expense	(2,084,000)	[4]	(2,082,000)	[4]	(6,368,000)	[4]	(6,306,000)	[4]
Segment core earnings before income taxes	1,695,000		444,000		5,650,000		2,386,000
Income tax (benefit)/expense	1,941,000		3,161,000		5,347,000		7,255,000
Segment core earnings before preferred stock dividends and attibution of income to non-controlling interest - preferred stock dividends	3,636,000		3,605,000		10,997,000		9,641,000
Preferred stock dividends	(719,000)		(719,000)		(2,159,000)		(2,159,000)
Non-controlling interest - preferred stock dividends	(5,547,000)		(5,547,000)		(16,641,000)		(16,641,000)
Segment core earnings	(2,630,000)		(2,661,000)		(7,803,000)		(9,159,000)
Total assets at carrying value	3,608,296,000		2,799,758,000		3,608,296,000		2,799,758,000
Total on - and off - balance sheet program assets at principal balance	0		0		0		0
Reconciling Adjustments
Segment Reporting Information [Line Items]
Segment interest and dividend income operating	(1,214,000)	[1]	(2,213,000)	[1]	(4,536,000)	[1]	(6,646,000)	[1]
Interest income related to consolidated trusts owned by third parties reclassified to guarantee fee income	190,000		782,000		1,463,000		2,495,000
Segment interest expense	(4,130,000)	[2]	(10,375,000)	[2]	(22,163,000)	[2]	(28,695,000)	[2]
Segment net effective spread	3,106,000		8,944,000		19,090,000		24,544,000
Segment guarantee fee income	(190,000)		(782,000)		(1,463,000)		(2,495,000)
Other income/(expense)	1,692,000	[3]	(60,869,000)	[3]	(23,391,000)	[3]	(68,002,000)	[3]
Segment non interest income	1,502,000		(61,651,000)		(24,854,000)		(70,497,000)
(Provision for)/release of loan losses	0		0		0		0
Release of (provision for) losses	0		0		0		0
Other non-interest expense	0		0		0		0
Non-interest expense	0	[4]	0	[4]	0	[4]	0	[4]
Segment core earnings before income taxes	4,608,000		(52,707,000)		(5,764,000)		(45,953,000)
Income tax (benefit)/expense	(1,612,000)		18,447,000		2,018,000		16,083,000
Segment core earnings before preferred stock dividends and attibution of income to non-controlling interest - preferred stock dividends	2,996,000	[5]	(34,260,000)	[5]	(3,746,000)	[5]	(29,870,000)	[5]
Preferred stock dividends	0		0		0		0
Non-controlling interest - preferred stock dividends	0		0		0		0
Segment core earnings	2,996,000	[5]	(34,260,000)	[5]	(3,746,000)	[5]	(29,870,000)	[5]
Total assets at carrying value	0		0		0		0
Total on - and off - balance sheet program assets at principal balance	$ 0		$ 0		$ 0		$ 0

[1] Includes reconciling adjustments for yield maintenance income and amortization of premiums on assets consolidated at fair value to reflect core earnings amounts.

[2] Based on effective funding cost determined for each operating segment, including expenses related to interest rate swaps not designated as hedges, which are included in Gains/(losses) on financial derivatives and hedging activities on the GAAP financial statements.

[3] Includes reconciling adjustments for the reclassification of yield maintenance income and expenses related to interest rate swaps not designated as hedges and fair value adjustments on financial derivatives and trading assets. Also includes a reconciling adjustment related to the recognition of deferred gains over the estimated lives of certain Farmer Mac II Guaranteed Securities and USDA Guaranteed Securities.

[4] Includes directly attributable costs and an allocation of indirectly attributable costs based on headcount.

[5] Net adjustments to reconcile core earnings before income taxes; core earnings before preferred stock dividends and attribution of income to non-controlling interest - preferred stock dividends; and segment core earnings to corresponding GAAP measures: (loss)/income before income taxes, net income, and net (loss)/income attributable to common stockholders, respectively.