Business Segment Reporting (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended							12 Months Ended						15 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010		Sep. 30, 2012
Segment Reporting Information [Line Items]
Total interest income	$ 56,151	$ 63,810	$ 71,578	$ 73,131	$ 72,642	$ 66,852	$ 64,072	$ 264,670		$ 274,687		$ 238,711		$ 71,121
Interest income related to consolidated trusts owned by third parties reclassified to guarantee fee income								0		0		0
Total interest expense	33,358	33,448	36,961	38,923	39,277	37,640	37,053	142,690		153,382		142,668		39,412
Net interest income	22,793	30,362	34,617	34,208	33,365	29,212	27,019	121,980		121,305		96,043		31,709
Guarantee and commitment fees	6,568	6,401	6,064	5,930	5,966	6,320	6,387	24,963		24,821		24,091		6,148
Other income/(expense)								(21,228)		(72,210)		(19,117)
Non-interest income/(loss)	8,374	8,464	(27,281)	14,178	854	(7,885)	15,047	3,735		(47,389)		4,974		(55,405)
Provision for loan losses	(4,354)	(137)	1,220	(420)	482	(160)	(1,281)	(3,691)		(610)		(1,893)		349
Release of (provision for) losses								1,816		2,957		(2,417)
Other non-interest expense								(32,724)		(31,616)		(30,210)
Non-interest expense	6,109	7,748	9,209	7,842	7,240	7,191	6,678	30,908		28,659		32,627		7,550
Income/(loss) before income taxes	20,704	30,941	(653)	40,124	27,461	13,976	34,107	91,116		44,647		66,497		(30,897)
Income tax (benefit)/expense	(4,837)	(8,294)	2,629	(11,654)	(7,872)	(2,539)	(9,517)	(22,156)		(5,797)		(13,797)		14,131
Net income	15,867	22,647	1,976	28,470	19,589	11,437	24,590	68,960		38,850		52,700		(16,766)
Preferred stock dividends	(720)	(719)	(720)	(720)	(720)	(720)	(720)	(2,879)		(2,879)		(4,129)		(719)
Net Income (Loss) Attributable to Noncontrolling Interest - preferred stock dividends	(5,546)	(5,547)	(5,547)	(5,547)	(5,546)	(5,547)	(5,547)	(22,187)		(22,187)		(20,707)		(5,547)
Loss On Retirement Of Preferred Stock								0		0		(5,784)
Net income attributable to common stockholders	9,601	16,381	(4,291)	22,203	13,323	5,170	18,323	43,894		13,784		22,080		(23,032)
Total assets at carrying value	12,622,201				11,883,508			12,622,201		11,883,508		9,479,914
On and Off Balance Sheet Program Assets, At Principal Balance	13,015,188				11,913,302			13,015,188		11,913,302		12,216,709
Farmer Mac I [Member]
Segment Reporting Information [Line Items]
Segment interest and dividend income operating								131,714	[1]	146,653	[1]	109,220	[1]
Interest income related to consolidated trusts owned by third parties reclassified to guarantee fee income								(1,659)		(3,269)		(4,627)
Segment interest expense								(65,460)	[2]	(92,155)	[2]	(71,147)	[2]
Segment net effective spread								64,595		51,229		33,446
Segment guarantee fee income								22,095		22,525		22,270
Other income/(expense)								2,427	[3]	3,201	[3]	3,389	[3]
Segment non interest income								24,522		25,726		25,659
Provision for loan losses								(3,691)		(610)		(1,893)
Release of (provision for) losses								1,816		2,957		(2,417)
Other non-interest expense								(15,066)		(15,768)		(15,430)
Non-interest expense								13,250	[4]	12,811	[4]	17,847	[4]
Segment core earnings before income taxes								72,176		63,534		39,365
Income tax (benefit)/expense								(25,261)		(22,237)		(13,778)
Segment core earnings before preferred stock dividends and attibution of income to non-controlling interest - preferred stock dividends								46,915		41,297		25,587
Preferred stock dividends								0		0		0
Net Income (Loss) Attributable to Noncontrolling Interest - preferred stock dividends								0		0		0
Segment core earnings								46,915		41,297		25,587
Loss On Retirement Of Preferred Stock												0
Total assets at carrying value	5,190,136				4,840,519			5,190,136		4,840,519		2,800,367
On and Off Balance Sheet Program Assets, At Principal Balance	9,056,489				8,057,027			9,056,489		8,057,027		8,188,628
Farmer Mac II [Member]
Segment Reporting Information [Line Items]
Segment interest and dividend income operating								56,815	[1]	56,726	[1]	55,129	[1]
Interest income related to consolidated trusts owned by third parties reclassified to guarantee fee income								0		0		0
Segment interest expense								(45,560)	[2]	(45,937)	[2]	(45,076)	[2]
Segment net effective spread								11,255		10,789		10,053
Segment guarantee fee income								163		204		458
Other income/(expense)								599	[3]	283	[3]	299	[3]
Segment non interest income								762		487		757
Provision for loan losses								0		0		0
Release of (provision for) losses								0		0		0
Other non-interest expense								(3,065)		(2,752)		(2,796)
Non-interest expense								3,065	[4]	2,752	[4]	2,796	[4]
Segment core earnings before income taxes								8,952		8,524		8,014
Income tax (benefit)/expense								(3,134)		(2,983)		(2,805)
Segment core earnings before preferred stock dividends and attibution of income to non-controlling interest - preferred stock dividends								5,818		5,541		5,209
Preferred stock dividends								0		0		0
Net Income (Loss) Attributable to Noncontrolling Interest - preferred stock dividends								0		0		0
Segment core earnings								5,818		5,541		5,209
Loss On Retirement Of Preferred Stock												0
Total assets at carrying value	1,641,030				1,552,105			1,641,030		1,552,105		1,378,265
On and Off Balance Sheet Program Assets, At Principal Balance	1,615,579				1,513,177			1,615,579		1,513,177		1,385,398
Rural Utilities [Member]
Segment Reporting Information [Line Items]
Segment interest and dividend income operating								63,243	[1]	53,237	[1]	56,072	[1]
Interest income related to consolidated trusts owned by third parties reclassified to guarantee fee income								0		0		0
Segment interest expense								(50,796)	[2]	(40,950)	[2]	(44,207)	[2]
Segment net effective spread								12,447		12,287		11,865
Segment guarantee fee income								4,364		5,361		5,990
Other income/(expense)								466	[3]	0	[3]	1	[3]
Segment non interest income								4,830		5,361		5,991
Provision for loan losses								0		0		0
Release of (provision for) losses								0		0		0
Other non-interest expense								(5,809)		(4,923)		(4,335)
Non-interest expense								5,809	[4]	4,923	[4]	4,335	[4]
Segment core earnings before income taxes								11,468		12,725		13,521
Income tax (benefit)/expense								(4,013)		(4,454)		(4,733)
Segment core earnings before preferred stock dividends and attibution of income to non-controlling interest - preferred stock dividends								7,455		8,271		8,788
Preferred stock dividends								0		0		0
Net Income (Loss) Attributable to Noncontrolling Interest - preferred stock dividends								0		0		0
Segment core earnings								7,455		8,271		8,788
Loss On Retirement Of Preferred Stock												0
Total assets at carrying value	2,398,809				2,421,904			2,398,809		2,421,904		2,727,332
On and Off Balance Sheet Program Assets, At Principal Balance	2,343,120				2,343,098			2,343,120		2,343,098		2,642,683
Corporate
Segment Reporting Information [Line Items]
Segment interest and dividend income operating								24,729	[1]	28,117	[1]	27,497	[1]
Interest income related to consolidated trusts owned by third parties reclassified to guarantee fee income								0		0		0
Segment interest expense								(6,469)	[2]	(13,003)	[2]	(16,384)	[2]
Segment net effective spread								18,260		15,114		11,113
Segment guarantee fee income								0		0		0
Other income/(expense)								(2,113)	[3]	(2,272)	[3]	(1,711)	[3]
Segment non interest income								(2,113)		(2,272)		(1,711)
Provision for loan losses								0		0		0
Release of (provision for) losses								0		0		0
Other non-interest expense								(8,784)		(8,173)		(7,649)
Non-interest expense								8,784	[4]	8,173	[4]	7,649	[4]
Segment core earnings before income taxes								7,363		4,669		1,753
Income tax (benefit)/expense								7,157		8,195		8,864
Segment core earnings before preferred stock dividends and attibution of income to non-controlling interest - preferred stock dividends								14,520		12,864		10,617
Preferred stock dividends								(2,879)		(2,879)		(4,129)
Net Income (Loss) Attributable to Noncontrolling Interest - preferred stock dividends								(22,187)		(22,187)		(20,707)
Segment core earnings								(10,546)		(12,202)		(14,219)
Loss On Retirement Of Preferred Stock												0
Total assets at carrying value	3,392,226				3,068,980			3,392,226		3,068,980		2,573,950
On and Off Balance Sheet Program Assets, At Principal Balance	0				0			0		0		0
Reconciling Adjustments
Segment Reporting Information [Line Items]
Segment interest and dividend income operating								(11,831)	[1]	(10,046)	[1]	(9,207)	[1]
Interest income related to consolidated trusts owned by third parties reclassified to guarantee fee income								1,659		3,269		4,627
Segment interest expense								25,595	[2]	38,663	[2]	34,146	[2]
Segment net effective spread								15,423		31,886		29,566
Segment guarantee fee income								(1,659)		(3,269)		(4,627)
Other income/(expense)								(22,607)	[3]	(73,422)	[3]	(21,095)	[3]
Segment non interest income								(24,266)		(76,691)		(25,722)
Provision for loan losses								0		0		0
Release of (provision for) losses								0		0		0
Other non-interest expense								0		0		0
Non-interest expense								0	[4]	0	[4]	0	[4]
Segment core earnings before income taxes								(8,843)		(44,805)		3,844
Income tax (benefit)/expense								3,095		15,682		(1,345)
Segment core earnings before preferred stock dividends and attibution of income to non-controlling interest - preferred stock dividends								(5,748)	[5]	(29,123)	[5]	2,499	[5]
Preferred stock dividends								0		0		0
Net Income (Loss) Attributable to Noncontrolling Interest - preferred stock dividends								0		0		0
Segment core earnings								(5,748)	[5]	(29,123)	[5]	(3,285)	[5]
Loss On Retirement Of Preferred Stock												(5,784)
Total assets at carrying value	0				0			0		0		0
On and Off Balance Sheet Program Assets, At Principal Balance	$ 0				$ 0			$ 0		$ 0		$ 0

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

[2] (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 "Losses on financial derivatives and hedging activities" on the GAAP financial statements.

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

[5] (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: income before income taxes, net income, and net income attributable to common stockholders, respectively.