Business Segment Reporting - Core Earnings - Business Segments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016		Mar. 31, 2015		Dec. 31, 2015
Segment Reporting Information, Profit (Loss) [Abstract]
Interest Income	$ 73,891	[1]	$ 63,951	[2]
Interest Income Reclassification	0		0
Total interest expense	(40,251)	[3]	(33,162)	[4]
Net effective spread	33,640		30,789
Guarantee and commitment fees	3,626		3,377
Other Non-Interest Income (Expense), Excluding Guarantee and Commitment Fees	(6,332)	[5]	(2,902)	[6]
Non-interest (loss)/income	(2,706)		475
Provision for loan losses	(49)		(76)
(Release of)/provision for reserve for losses	(14)		772
Noninterest Expense, Excluding Loan, Lease and Other Losses	(9,952)		(9,115)
Non-interest expense	(9,966)	[7]	(8,343)	[8]
Income before income taxes	20,919		22,845
Income tax expense	(7,335)		(4,231)
Net income	13,584		18,614
Preferred Stock Dividends, Income Statement Impact	(3,295)		(3,295)
Less: Net loss/(income) attributable to non-controlling interest	28		(5,354)
Loss on retirement of preferred stock	0		(8,147)
Net Income (Loss) Available to Common Stockholders, Basic	10,317		1,818
Segment Reporting Information, Additional Information [Abstract]
Assets	16,156,028		14,849,685		$ 15,540,354
On and Off Balance Sheet Program Assets, At Principal Balance	16,215,572		14,660,217
Farm & Ranch [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Interest Income	24,852	[1]	21,968	[2]
Interest Income Reclassification	(1,043)		(635)
Total interest expense	(14,348)	[3]	(11,219)	[4]
Net effective spread	9,461		10,114
Guarantee and commitment fees	3,909		3,633
Other Non-Interest Income (Expense), Excluding Guarantee and Commitment Fees	97	[5]	87	[6]
Non-interest (loss)/income	4,006		3,720
Provision for loan losses	(49)		(76)
(Release of)/provision for reserve for losses	(14)		772
Noninterest Expense, Excluding Loan, Lease and Other Losses	(4,161)		(4,326)
Non-interest expense	(4,175)	[7]	(3,554)	[8]
Segment core earnings before income taxes	9,243		10,204
Income tax expense	(3,236)		(3,571)
Segment core earnings before preferred stock dividends and attibution of income to non-controlling interest - preferred stock dividends	6,007		6,633
Preferred Stock Dividends, Income Statement Impact	0		0
Less: Net loss/(income) attributable to non-controlling interest	0		0
Loss on retirement of preferred stock			0
Segment core earnings	6,007		6,633
Segment Reporting Information, Additional Information [Abstract]
Assets	3,115,749		2,637,743
On and Off Balance Sheet Program Assets, At Principal Balance	5,713,789		5,347,248
USDA Guarantees [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Interest Income	15,282	[1]	14,348	[2]
Interest Income Reclassification	0		0
Total interest expense	(10,974)	[3]	(10,123)	[4]
Net effective spread	4,308		4,225
Guarantee and commitment fees	7		(6)
Other Non-Interest Income (Expense), Excluding Guarantee and Commitment Fees	58	[5]	59	[6]
Non-interest (loss)/income	65		53
Provision for loan losses	0		0
(Release of)/provision for reserve for losses	0		0
Noninterest Expense, Excluding Loan, Lease and Other Losses	(1,093)		(385)
Non-interest expense	(1,093)	[7]	(385)	[8]
Segment core earnings before income taxes	3,280		3,893
Income tax expense	(1,148)		(1,363)
Segment core earnings before preferred stock dividends and attibution of income to non-controlling interest - preferred stock dividends	2,132		2,530
Preferred Stock Dividends, Income Statement Impact	0		0
Less: Net loss/(income) attributable to non-controlling interest	0		0
Loss on retirement of preferred stock			0
Segment core earnings	2,132		2,530
Segment Reporting Information, Additional Information [Abstract]
Assets	1,987,855		1,876,337
On and Off Balance Sheet Program Assets, At Principal Balance	1,929,582		1,814,918
Rural Utilities [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Interest Income	6,829	[1]	6,585	[2]
Interest Income Reclassification	0		0
Total interest expense	(4,291)	[3]	(3,781)	[4]
Net effective spread	2,538		2,804
Guarantee and commitment fees	295		0
Other Non-Interest Income (Expense), Excluding Guarantee and Commitment Fees	0	[5]	0	[6]
Non-interest (loss)/income	295		0
Provision for loan losses	0		0
(Release of)/provision for reserve for losses	0		0
Noninterest Expense, Excluding Loan, Lease and Other Losses	(831)		(866)
Non-interest expense	(831)	[7]	(866)	[8]
Segment core earnings before income taxes	2,002		1,938
Income tax expense	(701)		(678)
Segment core earnings before preferred stock dividends and attibution of income to non-controlling interest - preferred stock dividends	1,301		1,260
Preferred Stock Dividends, Income Statement Impact	0		0
Less: Net loss/(income) attributable to non-controlling interest	0		0
Loss on retirement of preferred stock			0
Segment core earnings	1,301		1,260
Segment Reporting Information, Additional Information [Abstract]
Assets	1,002,691		970,020
On and Off Balance Sheet Program Assets, At Principal Balance	1,510,575		968,117
Institutional Credit [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Interest Income	20,268	[1]	19,299	[2]
Interest Income Reclassification	0		0
Total interest expense	(9,178)	[3]	(8,874)	[4]
Net effective spread	11,090		10,425
Guarantee and commitment fees	458		385
Other Non-Interest Income (Expense), Excluding Guarantee and Commitment Fees	0	[5]	0	[6]
Non-interest (loss)/income	458		385
Provision for loan losses	0		0
(Release of)/provision for reserve for losses	0		0
Noninterest Expense, Excluding Loan, Lease and Other Losses	(539)		(535)
Non-interest expense	(539)	[7]	(535)	[8]
Segment core earnings before income taxes	11,009		10,275
Income tax expense	(3,852)		(3,596)
Segment core earnings before preferred stock dividends and attibution of income to non-controlling interest - preferred stock dividends	7,157		6,679
Preferred Stock Dividends, Income Statement Impact	0		0
Less: Net loss/(income) attributable to non-controlling interest	0		0
Loss on retirement of preferred stock			0
Segment core earnings	7,157		6,679
Segment Reporting Information, Additional Information [Abstract]
Assets	5,731,346		5,594,736
On and Off Balance Sheet Program Assets, At Principal Balance	7,061,626		6,529,934
Corporate Segment [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Interest Income	6,681	[1]	2,865	[2]
Interest Income Reclassification	0		0
Total interest expense	(4,129)	[3]	(1,176)	[4]
Net effective spread	2,552		1,689
Guarantee and commitment fees	0		0
Other Non-Interest Income (Expense), Excluding Guarantee and Commitment Fees	(672)	[5]	(552)	[6]
Non-interest (loss)/income	(672)		(552)
Provision for loan losses	0		0
(Release of)/provision for reserve for losses	0		0
Noninterest Expense, Excluding Loan, Lease and Other Losses	(3,328)		(3,003)
Non-interest expense	(3,328)	[7]	(3,003)	[8]
Segment core earnings before income taxes	(1,448)		(1,866)
Income tax expense	493		2,516
Segment core earnings before preferred stock dividends and attibution of income to non-controlling interest - preferred stock dividends	(955)		650
Preferred Stock Dividends, Income Statement Impact	(3,295)		(3,295)
Less: Net loss/(income) attributable to non-controlling interest	28		(5,354)
Loss on retirement of preferred stock			0
Segment core earnings	(4,222)		(7,999)
Segment Reporting Information, Additional Information [Abstract]
Assets	4,318,387		3,770,849
Segment Reconciling Items [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Interest Income	(21)	[1]	(1,114)	[2]
Interest Income Reclassification	1,043		635
Total interest expense	2,669	[3]	2,011	[4]
Net effective spread	3,691		1,532
Guarantee and commitment fees	(1,043)		(635)
Other Non-Interest Income (Expense), Excluding Guarantee and Commitment Fees	(5,815)	[5]	(2,496)	[6]
Non-interest (loss)/income	(6,858)		(3,131)
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
Non-interest expense	0	[7]	0	[8]
Segment core earnings before income taxes	(3,167)	[9]	(1,599)	[10]
Income tax expense	1,109		2,461
Segment core earnings before preferred stock dividends and attibution of income to non-controlling interest - preferred stock dividends	(2,058)	[9]	862	[10]
Preferred Stock Dividends, Income Statement Impact	0		0
Less: Net loss/(income) attributable to non-controlling interest	0		0
Loss on retirement of preferred stock			(8,147)
Segment core earnings	(2,058)	[9]	(7,285)
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.

[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.

[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 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.

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

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

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