Business Segment Reporting - Core Earnings - Business Segments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014		Dec. 31, 2014
Segment Reporting Information, Profit (Loss) [Abstract]
Interest and Dividend Income, Operating	$ 63,951	[1]	$ 52,452	[2]
Interest Income Reclassification	0		0
Total interest expense	(33,162)	[3]	(34,726)	[4]
Net effective spread	30,789		17,726
Guarantee and commitment fees	3,377		3,784
Other Non-Interest Income (Expense), Excluding Guarantee and Commitment Fees	(2,902)	[5]	(6,819)	[6]
Non-interest income/(loss)	475		(3,035)
Provision for loan losses	(76)		(573)
(Release of)/provision for reserve for losses	772		(101)
Noninterest Expense, Excluding Loan, Lease and Other Losses	(9,115)		(7,846)
Noninterest Expense	(8,343)	[7]	(7,947)	[7]
Income before income taxes	22,845		6,171
Income tax expense	(4,231)		1,141
Net income	18,614		7,312
Preferred Stock Dividends, Income Statement Impact	(3,295)		(952)
Less: Net income attributable to non-controlling interest	(5,354)		(5,547)
Loss on retirement of preferred stock	(8,147)		0
Net income attributable to common stockholders	1,818		813
Segment Reporting Information, Additional Information [Abstract]
Assets	14,849,685		13,554,353		14,287,821
On and Off Balance Sheet Program Assets, At Principal Balance	14,660,217		14,108,203
Farm & Ranch [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Interest and Dividend Income, Operating	21,968	[1]	18,339	[2]
Interest Income Reclassification	(635)		(531)
Total interest expense	(11,219)	[3]	(10,694)	[4]
Net effective spread	10,114		7,114
Guarantee and commitment fees	3,633		3,909
Other Non-Interest Income (Expense), Excluding Guarantee and Commitment Fees	87	[5]	130	[6]
Non-interest income/(loss)	3,720		4,039
Provision for loan losses	(76)		(573)
(Release of)/provision for reserve for losses	772		(101)
Noninterest Expense, Excluding Loan, Lease and Other Losses	(4,326)		(3,552)
Noninterest Expense	(3,554)	[7]	(3,653)	[7]
Segment core earnings before income taxes	10,204		6,927
Income tax expense	(3,571)		(2,424)
Segment core earnings before preferred stock dividends and attibution of income to non-controlling interest - preferred stock dividends	6,633		4,503
Preferred Stock Dividends, Income Statement Impact	0		0
Less: Net income attributable to non-controlling interest	0		0
Loss on retirement of preferred stock	0
Segment core earnings	6,633		4,503
Segment Reporting Information, Additional Information [Abstract]
Assets	2,637,743		2,272,643
On and Off Balance Sheet Program Assets, At Principal Balance	5,347,248		5,293,975
USDA Guarantees [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Interest and Dividend Income, Operating	14,348	[1]	12,959	[2]
Interest Income Reclassification	0		0
Total interest expense	(10,123)	[3]	(9,175)	[4]
Net effective spread	4,225		3,784
Guarantee and commitment fees	(6)		26
Other Non-Interest Income (Expense), Excluding Guarantee and Commitment Fees	59	[5]	28	[6]
Non-interest income/(loss)	53		54
Provision for loan losses	0		0
(Release of)/provision for reserve for losses	0		0
Noninterest Expense, Excluding Loan, Lease and Other Losses	(385)		(731)
Noninterest Expense	(385)	[7]	(731)	[7]
Segment core earnings before income taxes	3,893		3,107
Income tax expense	(1,363)		(1,087)
Segment core earnings before preferred stock dividends and attibution of income to non-controlling interest - preferred stock dividends	2,530		2,020
Preferred Stock Dividends, Income Statement Impact	0		0
Less: Net income attributable to non-controlling interest	0		0
Loss on retirement of preferred stock	0
Segment core earnings	2,530		2,020
Segment Reporting Information, Additional Information [Abstract]
Assets	1,876,337		1,691,056
On and Off Balance Sheet Program Assets, At Principal Balance	1,814,918		1,686,696
Rural Utilities [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Interest and Dividend Income, Operating	6,585	[1]	7,744	[2]
Interest Income Reclassification	0		0
Total interest expense	(3,781)	[3]	(5,754)	[4]
Net effective spread	2,804		1,990
Guarantee and commitment fees	0		0
Other Non-Interest Income (Expense), Excluding Guarantee and Commitment Fees	0	[5]	0	[6]
Non-interest income/(loss)	0		0
Provision for loan losses	0		0
(Release of)/provision for reserve for losses	0		0
Noninterest Expense, Excluding Loan, Lease and Other Losses	(866)		(777)
Noninterest Expense	(866)	[7]	(777)	[7]
Segment core earnings before income taxes	1,938		1,213
Income tax expense	(678)		(425)
Segment core earnings before preferred stock dividends and attibution of income to non-controlling interest - preferred stock dividends	1,260		788
Preferred Stock Dividends, Income Statement Impact	0		0
Less: Net income attributable to non-controlling interest	0		0
Loss on retirement of preferred stock	0
Segment core earnings	1,260		788
Segment Reporting Information, Additional Information [Abstract]
Assets	970,020		1,030,422
On and Off Balance Sheet Program Assets, At Principal Balance	968,117		1,027,246
Institutional Credit [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Interest and Dividend Income, Operating	19,299	[1]	20,380	[2]
Interest Income Reclassification	0		0
Total interest expense	(8,874)	[3]	(10,974)	[4]
Net effective spread	10,425		9,406
Guarantee and commitment fees	385		380
Other Non-Interest Income (Expense), Excluding Guarantee and Commitment Fees	0	[5]	0	[6]
Non-interest income/(loss)	385		380
Provision for loan losses	0		0
(Release of)/provision for reserve for losses	0		0
Noninterest Expense, Excluding Loan, Lease and Other Losses	(535)		(445)
Noninterest Expense	(535)	[7]	(445)	[7]
Segment core earnings before income taxes	10,275		9,341
Income tax expense	(3,596)		(3,269)
Segment core earnings before preferred stock dividends and attibution of income to non-controlling interest - preferred stock dividends	6,679		6,072
Preferred Stock Dividends, Income Statement Impact	0		0
Less: Net income attributable to non-controlling interest	0		0
Loss on retirement of preferred stock	0
Segment core earnings	6,679		6,072
Segment Reporting Information, Additional Information [Abstract]
Assets	5,594,736		5,157,887
On and Off Balance Sheet Program Assets, At Principal Balance	6,529,934		6,100,286
Corporate [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Interest and Dividend Income, Operating	2,865	[1]	5,235	[2]
Interest Income Reclassification	0		0
Total interest expense	(1,176)	[3]	(1,093)	[4]
Net effective spread	1,689		4,142
Guarantee and commitment fees	0		0
Other Non-Interest Income (Expense), Excluding Guarantee and Commitment Fees	(552)	[5]	(571)	[6]
Non-interest income/(loss)	(552)		(571)
Provision for loan losses	0		0
(Release of)/provision for reserve for losses	0		0
Noninterest Expense, Excluding Loan, Lease and Other Losses	(3,003)		(2,341)
Noninterest Expense	(3,003)	[7]	(2,341)	[7]
Segment core earnings before income taxes	(1,866)		1,230
Income tax expense	2,516		2,871
Segment core earnings before preferred stock dividends and attibution of income to non-controlling interest - preferred stock dividends	650		4,101
Preferred Stock Dividends, Income Statement Impact	(3,295)		(952)
Less: Net income attributable to non-controlling interest	(5,354)		(5,547)
Loss on retirement of preferred stock	0
Segment core earnings	(7,999)		(2,398)
Segment Reporting Information, Additional Information [Abstract]
Assets	3,770,849		3,402,345
Segment Reconciling Items [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Interest and Dividend Income, Operating	(1,114)	[1]	(12,205)	[2]
Interest Income Reclassification	635		531
Total interest expense	2,011	[3]	2,964	[4]
Net effective spread	1,532		(8,710)
Guarantee and commitment fees	(635)		(531)
Other Non-Interest Income (Expense), Excluding Guarantee and Commitment Fees	(2,496)	[5]	(6,406)	[6]
Non-interest income/(loss)	(3,131)		(6,937)
Provision for loan losses	0		0
(Release of)/provision for reserve for losses	0		0
Noninterest Expense, Excluding Loan, Lease and Other Losses	0		0
Noninterest Expense	0	[7]	0	[7]
Segment core earnings before income taxes	(1,599)	[8]	(15,647)	[9]
Income tax expense	2,461		5,475
Segment core earnings before preferred stock dividends and attibution of income to non-controlling interest - preferred stock dividends	862	[8]	(10,172)	[9]
Preferred Stock Dividends, Income Statement Impact	0		0
Less: Net income attributable to non-controlling interest	0		0
Loss on retirement of preferred stock	(8,147)
Segment core earnings	(7,285)	[8]	(10,172)	[9]
Segment Reporting Information, Additional Information [Abstract]
Assets	0		0
On and Off Balance Sheet Program Assets, At Principal Balance	$ 0		$ 0

[1] Includes reconciling adjustments for the amortization of premiums and discounts on assets consolidated at fair value to reflect core earnings amounts and interest income related to securities purchased under agreements to resell

[2] Includes reconciling adjustments for the amortization of premiums and discounts on assets consolidated at fair value to reflect core earnings amounts

[3] 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 consolidated financial statements. Includes reconciling adjustments for interest expense related to securities sold, not yet purchased

[4] 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 consolidated financial statements.

[5] Includes interest income and interest expense related to securities purchased under agreements to resell and securities sold, not yet purchased, respectively; reconciling adjustments for the reclassification of expenses related to interest rate swaps not designated as hedges and fair value adjustments on financial derivatives and trading assets; and a reconciling adjustment related to the recognition of deferred gains over the estimated lives of certain Farmer Mac Guaranteed Securities and USDA Securities

[6] Includes reconciling adjustments for the reclassification of 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 Guaranteed Securities and USDA Securities

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

[8] 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 income measures: income before income taxes, net income, and net income attributable to common stockholders, respectively

[9] 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 income measures: income before income taxes, net income, and net income attributable to common stockholders, respectively.