Business Segment Reporting - Core Earnings - Business Segments (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016		Dec. 31, 2015		Dec. 31, 2014
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	$ 36,713	$ 35,563	$ 34,358	$ 33,640	$ 30,971	$ 32,183	$ 31,864	$ 30,789	$ 140,274		$ 125,807		$ 70,347
Less: reconciling adjustments(1)(2)(3)									0	[1],[2],[3]	0	[4],[5],[6]	0	[7],[8],[9],[10]
Net Effective Spread									0		0		0
Guarantee and commitment fees	3,789	3,798	3,655	3,626	3,780	3,532	3,388	3,377	14,868	[3]	14,077	[6]	14,694	[9]
Other income/(expense)(3)(4)									5,600	[2],[11]	6,064	[5],[12]	18,596	[8],[10],[13]
Non-interest income	19,307	4,101	(234)	(2,706)	6,440	(4,981)	18,207	475	20,468		20,141		33,290
(Provision for)/release of loan losses	(461)	(191)	(364)	(49)	(3,366)	1,164	(110)	(76)	(1,065)		(2,388)		961
Provision for losses									63		2,180		2,205
Noninterest Expense, Excluding Loan, Lease and Other Losses									(40,383)		(37,662)		(33,697)
Non-interest expense	(10,977)	(9,303)	(10,074)	(9,966)	(5,865)	(10,421)	(10,853)	(8,343)	(40,320)	[14]	(35,482)	[15]	(31,492)	[16]
Income before income taxes	44,582	30,170	23,686	20,919	28,180	17,945	39,108	22,845	119,357		108,078		73,106
Income tax expense	(15,793)	(10,529)	(8,400)	(7,335)	(9,912)	(6,327)	(13,769)	(4,231)	(42,057)		(34,239)		(2,824)
Net income	28,789	19,641	15,286	13,584	18,268	11,618	25,339	18,614	77,300		73,839		70,282
Preferred Stock Dividends, Income Statement Impact	(3,296)	(3,295)	(3,296)	(3,295)	(3,296)	(3,295)	(3,296)	(3,295)	(13,182)		(13,182)		(9,839)
Less: Net loss/(income) attributable to non-controlling interest	(28)	18	16	28	60	36	119	(5,354)	34		(5,139)		(22,192)
Loss on retirement of preferred stock					0	0	0	(8,147)	0		(8,147)		0
Net Income (Loss) Available to Common Stockholders, Basic	25,465	$ 16,364	$ 12,006	$ 10,317	15,032	$ 8,359	$ 22,162	$ 1,818	64,152		47,371		38,251
Segment Reporting Information, Additional Information [Abstract]
Assets	15,606,020				15,540,354				15,606,020		15,540,354		14,287,821
On and Off Balance Sheet Program Assets, At Principal Balance	17,399,475				15,898,820				17,399,475		15,898,820		14,597,758
Farm & Ranch [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income									47,219		43,270		36,373
Less: reconciling adjustments(1)(2)(3)									(6,831)	[1],[2],[3]	(4,466)	[4],[5],[6]	(4,550)	[7],[8],[9],[10]
Net Effective Spread									40,388		38,804		31,823
Guarantee and commitment fees									15,542	[3]	15,076	[6]	15,107	[9]
Other income/(expense)(3)(4)									539	[2],[11]	1,040	[5],[12]	762	[8],[10],[13]
Non-interest income									16,081		16,116		15,869
(Provision for)/release of loan losses									(1,065)		(2,388)		961
Provision for losses									63		2,180		2,205
Noninterest Expense, Excluding Loan, Lease and Other Losses									(16,206)		(16,876)		(15,180)
Non-interest expense									(16,143)	[14]	(14,696)	[15]	(12,975)	[16]
Segment core earnings before income taxes									39,261		37,836		35,678
Income tax expense									(13,743)		(13,188)		(12,486)
Segment core earnings before preferred stock dividends and attibution of income to non-controlling interest - preferred stock dividends									25,518		24,648		23,192
Preferred Stock Dividends, Income Statement Impact									0		0		0
Less: Net loss/(income) attributable to non-controlling interest									0		0		0
Loss on retirement of preferred stock											0
Segment core earnings									25,518		24,648		23,192
Segment Reporting Information, Additional Information [Abstract]
Assets	3,582,098				3,041,386				3,582,098		3,041,386		2,611,401
On and Off Balance Sheet Program Assets, At Principal Balance	6,139,304				5,725,299				6,139,304		5,725,299		5,417,174
USDA Guarantees [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income									21,865		17,751		17,362
Less: reconciling adjustments(1)(2)(3)									(2,446)	[1],[2],[3]	88	[4],[5],[6]	904	[7],[8],[9],[10]
Net Effective Spread									19,419		17,839		18,266
Guarantee and commitment fees									101	[3]	17	[6]	134	[9]
Other income/(expense)(3)(4)									222	[2],[11]	100	[5],[12]	63	[8],[10],[13]
Non-interest income									323		117		197
(Provision for)/release of loan losses									0		0		0
Provision for losses									0		0		0
Noninterest Expense, Excluding Loan, Lease and Other Losses									(4,200)		(3,449)		(2,955)
Non-interest expense									(4,200)	[14]	(3,449)	[15]	(2,955)	[16]
Segment core earnings before income taxes									15,542		14,507		15,508
Income tax expense									(5,439)		(5,176)		(5,430)
Segment core earnings before preferred stock dividends and attibution of income to non-controlling interest - preferred stock dividends									10,103		9,331		10,078
Preferred Stock Dividends, Income Statement Impact									0		0		0
Less: Net loss/(income) attributable to non-controlling interest									0		0		0
Loss on retirement of preferred stock											0
Segment core earnings									10,103		9,331		10,078
Segment Reporting Information, Additional Information [Abstract]
Assets	2,096,503				1,977,609				2,096,503		1,977,609		1,825,210
On and Off Balance Sheet Program Assets, At Principal Balance	2,094,375				1,918,277				2,094,375		1,918,277		1,798,034
Rural Utilities [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income									11,739		11,729		45
Less: reconciling adjustments(1)(2)(3)									(1,373)	[1],[2],[3]	(335)	[4],[5],[6]	10,696	[7],[8],[9],[10]
Net Effective Spread									10,366		11,394		10,741
Guarantee and commitment fees									1,694	[3]	397	[6]	0	[9]
Other income/(expense)(3)(4)									2	[2],[11]	25	[5],[12]	9	[8],[10],[13]
Non-interest income									1,696		422		9
(Provision for)/release of loan losses									0		0		0
Provision for losses									0		0		0
Noninterest Expense, Excluding Loan, Lease and Other Losses									(2,856)		(3,364)		(3,130)
Non-interest expense									(2,856)	[14]	(3,364)	[15]	(3,130)	[16]
Segment core earnings before income taxes									9,206		8,452		7,620
Income tax expense									(3,223)		(2,947)		(2,668)
Segment core earnings before preferred stock dividends and attibution of income to non-controlling interest - preferred stock dividends									5,983		5,505		4,952
Preferred Stock Dividends, Income Statement Impact									0		0		0
Less: Net loss/(income) attributable to non-controlling interest									0		0		0
Loss on retirement of preferred stock											0
Segment core earnings									5,983		5,505		4,952
Segment Reporting Information, Additional Information [Abstract]
Assets	1,012,014				1,019,279				1,012,014		1,019,279		995,082
On and Off Balance Sheet Program Assets, At Principal Balance	1,878,110				1,530,990				1,878,110		1,530,990		985,609
Institutional Credit [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income									48,756		44,970		41,870
Less: reconciling adjustments(1)(2)(3)									(3,205)	[1],[2],[3]	(1,515)	[4],[5],[6]	(2,814)	[7],[8],[9],[10]
Net Effective Spread									45,551		43,455		39,056
Guarantee and commitment fees									1,833	[3]	1,665	[6]	1,539	[9]
Other income/(expense)(3)(4)									0	[2],[11]	0	[5],[12]	0	[8],[10],[13]
Non-interest income									1,833		1,665		1,539
(Provision for)/release of loan losses									0		0		0
Provision for losses									0		0		0
Noninterest Expense, Excluding Loan, Lease and Other Losses									(3,786)		(2,109)		(1,891)
Non-interest expense									(3,786)	[14]	(2,109)	[15]	(1,891)	[16]
Segment core earnings before income taxes									43,598		43,011		38,704
Income tax expense									(15,258)		(15,054)		(13,548)
Segment core earnings before preferred stock dividends and attibution of income to non-controlling interest - preferred stock dividends									28,340		27,957		25,156
Preferred Stock Dividends, Income Statement Impact									0		0		0
Less: Net loss/(income) attributable to non-controlling interest									0		0		0
Loss on retirement of preferred stock											0
Segment core earnings									28,340		27,957		25,156
Segment Reporting Information, Additional Information [Abstract]
Assets	6,008,574				5,420,195				6,008,574		5,420,195		5,459,296
On and Off Balance Sheet Program Assets, At Principal Balance	7,287,686				6,724,254				7,287,686		6,724,254		6,396,941
Corporate Segment [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income									10,695		8,087		(25,303)
Less: reconciling adjustments(1)(2)(3)									(1,317)	[1],[2],[3]	(199)	[4],[5],[6]	39,110	[7],[8],[9],[10]
Net Effective Spread									9,378		7,888		13,807
Guarantee and commitment fees									0	[3]	0	[6]	0	[9]
Other income/(expense)(3)(4)									(231)	[2],[11]	(1,972)	[5],[12]	(4,913)	[8],[10],[13]
Non-interest income									(231)		(1,972)		(4,913)
(Provision for)/release of loan losses									0		0		0
Provision for losses									0		0		0
Noninterest Expense, Excluding Loan, Lease and Other Losses									(13,335)		(11,864)		(10,541)
Non-interest expense									(13,335)	[14]	(11,864)	[15]	(10,541)	[16]
Segment core earnings before income taxes									(4,188)		(5,948)		(1,647)
Income tax expense									1,185		3,803		23,347
Segment core earnings before preferred stock dividends and attibution of income to non-controlling interest - preferred stock dividends									(3,003)		(2,145)		21,700
Preferred Stock Dividends, Income Statement Impact									(13,182)		(13,182)		(9,839)
Less: Net loss/(income) attributable to non-controlling interest									34		(5,139)		(22,192)
Loss on retirement of preferred stock											0
Segment core earnings									(16,151)		(20,466)		(10,331)
Segment Reporting Information, Additional Information [Abstract]
Assets	2,906,831				4,081,885				2,906,831		4,081,885		3,396,832
Segment Reconciling Items [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income									0		0		0
Less: reconciling adjustments(1)(2)(3)									15,172	[1],[2],[3]	6,427	[4],[5],[6]	(43,346)	[7],[8],[9],[10]
Net Effective Spread									15,172		6,427		(43,346)
Guarantee and commitment fees									(4,302)	[3]	(3,078)	[6]	(2,086)	[9]
Other income/(expense)(3)(4)									5,068	[2],[11]	6,871	[5],[12]	22,675	[8],[10],[13]
Non-interest income									766		3,793		20,589
(Provision for)/release of loan losses									0		0		0
Provision for losses									0		0		0
Noninterest Expense, Excluding Loan, Lease and Other Losses									0		0		0
Non-interest expense									0	[14]	0	[15]	0	[16]
Segment core earnings before income taxes									15,938	[17]	10,220	[18]	(22,757)	[16]
Income tax expense									(5,579)		(1,677)		7,961
Segment core earnings before preferred stock dividends and attibution of income to non-controlling interest - preferred stock dividends									10,359	[17]	8,543	[18]	(14,796)	[16]
Preferred Stock Dividends, Income Statement Impact									0		0		0
Less: Net loss/(income) attributable to non-controlling interest									0		0		0
Loss on retirement of preferred stock											(8,147)
Segment core earnings									10,359	[17]	396	[18]	(14,796)	[16]
Segment Reporting Information, Additional Information [Abstract]
Assets	0				0				0		0		0
On and Off Balance Sheet Program Assets, At Principal Balance	$ 0				$ 0				$ 0		$ 0		$ 0

[1] Excludes the amortization of premiums and discounts on assets consolidated at fair value, originally included in interest income, to reflect core earnings amounts.

[2] Includes the reclassification of interest expense related to interest rate swaps not designated as hedges, which are included in "Gains/(losses) on financial derivatives and hedging activities" on the consolidated financial statements, to determine the effective funding cost for each operating segment.

[3] Includes the reclassification of interest income and interest expense from consolidated trusts owned by third parties to guarantee and commitment fees, to reflect management's view that the net interest income Farmer Mac earns is effectively a guarantee fee.

[4] Excludes the amortization of premiums and discounts on assets consolidated at fair value, originally included in interest income, to reflect core earnings amounts.

[5] Includes the reclassification of interest expense related to interest rate swaps not designated as hedges, which are included in "Gains/(losses) on financial derivatives and hedging activities" on the consolidated financial statements, to determine the effective funding cost for each operating segment.

[6] Includes the reclassification of interest income and interest expense from consolidated trusts owned by third parties to guarantee and commitment fees, to reflect management's view that the net interest income Farmer Mac earns is effectively a guarantee fee.

[7] Excludes the amortization of premiums and discounts on assets consolidated at fair value, originally included in interest income, to reflect core earnings amounts.

[8] Includes the reclassification of interest expense related to interest rate swaps not designated as hedges, which are included in "Gains/(losses) on financial derivatives and hedging activities" on the consolidated financial statements, to determine the effective funding cost for each operating segment.

[9] Includes the reclassification of interest income and interest expense from consolidated trusts owned by third parties to guarantee and commitment fees, to reflect management's view that the net interest income Farmer Mac earns is effectively a guarantee fee.

[10] Includes the reclassification of interest income and interest expense related to securities purchased under agreements to resell and securities sold, not yet purchased, respectively to other income/(expense).

[11] Includes reconciling adjustments for 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. In 2016 and prior periods, fair value adjustments on financial derivatives included variation margin payment amounts because those amounts were considered to be collateral of the related exposure and were accounted for as unrealized gains or losses. However, effective first quarter 2017, CME implemented a change in its rules related to the exchange of variation margin, whereby variation margin payments will be considered a partial settlement of the respective derivatives contracts rather than as pledged collateral, and accounted for as realized gains and losses. See Note 6 for more information about this rule change. Farmer Mac believes that even though these variation margin amounts will be accounted for as realized gains or losses on financial derivatives and hedging activities as a result of the CME rule change, their economic character will remain the same as they were before the change. The fair value fluctuations related to the exchange of variation margin, whether considered a partial settlement of or the pledge of collateral under a derivatives contract, are not expected to have a cumulative net impact on Farmer Mac's financial condition or results of operations reported in accordance with GAAP because the related financial instruments are expected to be held to maturity. Therefore, beginning in 2017, this reconciling adjustment will include realized gains and losses on financial derivatives centrally cleared through CME resulting from the exchange of variation margin. As a result, core earnings subsequent to 2016 will be presented on a consistent basis with core earnings in 2016 and prior periods.

[12] Includes reconciling adjustments for 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.

[13] Includes reconciling adjustments for 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.

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

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

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

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

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