Business Segment Reporting - Core Earnings - Business Segments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017		Mar. 31, 2016		Dec. 31, 2016
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	$ 37,071		$ 33,640
Less: reconciling adjustments(1)(2)(3)	0	[1],[2],[3]	0	[4],[5],[6]
Net Effective Spread	0		0
Guarantee and commitment fees	3,844	[3]	3,626	[6]
Other income/(expense)(3)(4)	2,952	[2],[7]	(6,332)	[5],[8]
Non-interest income/(loss)	6,796		(2,706)
Provision for loan losses	(637)		(49)
Provision for losses	193		(14)
Noninterest Expense, Excluding Loan, Lease and Other Losses	(10,742)		(9,952)
Non-interest expense	(10,549)	[9]	(9,966)	[10]
Income before income taxes	32,681		20,919
Income tax expense	(10,786)		(7,335)
Net income	21,895		13,584
Preferred Stock Dividends, Income Statement Impact	(3,295)		(3,295)
Less: Net loss attributable to non-controlling interest	15		28
Net Income (Loss) Available to Common Stockholders, Basic	18,615		10,317
Segment Reporting Information, Additional Information [Abstract]
Assets	15,931,757		16,156,028		$ 15,606,020
On and Off Balance Sheet Program Assets, At Principal Balance	17,844,541		16,215,572
Farm & Ranch [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	12,754		11,127
Less: reconciling adjustments(1)(2)(3)	(2,070)	[1],[2],[3]	(1,666)	[4],[5],[6]
Net Effective Spread	10,684		9,461
Guarantee and commitment fees	4,295	[3]	3,909	[6]
Other income/(expense)(3)(4)	194	[2],[7]	97	[5],[8]
Non-interest income/(loss)	4,489		4,006
Provision for loan losses	(637)		(49)
Provision for losses	193		(14)
Noninterest Expense, Excluding Loan, Lease and Other Losses	(4,065)		(4,161)
Non-interest expense	(3,872)	[9]	(4,175)	[10]
Segment core earnings before income taxes	10,664		9,243
Income tax expense	(3,732)		(3,236)
Segment core earnings before preferred stock dividends and attibution of income to non-controlling interest - preferred stock dividends	6,932		6,007
Preferred Stock Dividends, Income Statement Impact	0		0
Less: Net loss attributable to non-controlling interest	0		0
Segment core earnings	6,932		6,007
Segment Reporting Information, Additional Information [Abstract]
Assets	3,693,360		3,115,749
On and Off Balance Sheet Program Assets, At Principal Balance	6,240,467		5,713,789
USDA Guarantees [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	5,283		5,052
Less: reconciling adjustments(1)(2)(3)	(580)	[1],[2],[3]	(744)	[4],[5],[6]
Net Effective Spread	4,703		4,308
Guarantee and commitment fees	74	[3]	7	[6]
Other income/(expense)(3)(4)	14	[2],[7]	58	[5],[8]
Non-interest income/(loss)	88		65
Provision for loan losses	0		0
Provision for losses	0		0
Noninterest Expense, Excluding Loan, Lease and Other Losses	(1,087)		(1,093)
Non-interest expense	(1,087)	[9]	(1,093)	[10]
Segment core earnings before income taxes	3,704		3,280
Income tax expense	(1,296)		(1,148)
Segment core earnings before preferred stock dividends and attibution of income to non-controlling interest - preferred stock dividends	2,408		2,132
Preferred Stock Dividends, Income Statement Impact	0		0
Less: Net loss attributable to non-controlling interest	0		0
Segment core earnings	2,408		2,132
Segment Reporting Information, Additional Information [Abstract]
Assets	2,109,264		1,987,855
On and Off Balance Sheet Program Assets, At Principal Balance	2,149,697		1,929,582
Rural Utilities [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	2,948		2,864
Less: reconciling adjustments(1)(2)(3)	(309)	[1],[2],[3]	(326)	[4],[5],[6]
Net Effective Spread	2,639		2,538
Guarantee and commitment fees	492	[3]	295	[6]
Other income/(expense)(3)(4)	5	[2],[7]	0	[5],[8]
Non-interest income/(loss)	497		295
Provision for loan losses	0		0
Provision for losses	0		0
Noninterest Expense, Excluding Loan, Lease and Other Losses	(587)		(831)
Non-interest expense	(587)	[9]	(831)	[10]
Segment core earnings before income taxes	2,549		2,002
Income tax expense	(892)		(701)
Segment core earnings before preferred stock dividends and attibution of income to non-controlling interest - preferred stock dividends	1,657		1,301
Preferred Stock Dividends, Income Statement Impact	0		0
Less: Net loss attributable to non-controlling interest	0		0
Segment core earnings	1,657		1,301
Segment Reporting Information, Additional Information [Abstract]
Assets	1,005,187		1,002,691
On and Off Balance Sheet Program Assets, At Principal Balance	1,868,794		1,510,575
Institutional Credit [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	13,502		11,749
Less: reconciling adjustments(1)(2)(3)	(921)	[1],[2],[3]	(659)	[4],[5],[6]
Net Effective Spread	12,581		11,090
Guarantee and commitment fees	455	[3]	458	[6]
Other income/(expense)(3)(4)	0	[2],[7]	0	[5],[8]
Non-interest income/(loss)	455		458
Provision for loan losses	0		0
Provision for losses	0		0
Noninterest Expense, Excluding Loan, Lease and Other Losses	(1,521)		(539)
Non-interest expense	(1,521)	[9]	(539)	[10]
Segment core earnings before income taxes	11,515		11,009
Income tax expense	(4,030)		(3,852)
Segment core earnings before preferred stock dividends and attibution of income to non-controlling interest - preferred stock dividends	7,485		7,157
Preferred Stock Dividends, Income Statement Impact	0		0
Less: Net loss attributable to non-controlling interest	0		0
Segment core earnings	7,485		7,157
Segment Reporting Information, Additional Information [Abstract]
Assets	6,315,591		5,731,346
On and Off Balance Sheet Program Assets, At Principal Balance	7,585,583		7,061,626
Corporate Segment [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	2,584		2,848
Less: reconciling adjustments(1)(2)(3)	(325)	[1],[2],[3]	(296)	[4],[5],[6]
Net Effective Spread	2,259		2,552
Guarantee and commitment fees	0	[3]	0	[6]
Other income/(expense)(3)(4)	843	[2],[7]	(672)	[5],[8]
Non-interest income/(loss)	843		(672)
Provision for loan losses	0		0
Provision for losses	0		0
Noninterest Expense, Excluding Loan, Lease and Other Losses	(3,482)		(3,328)
Non-interest expense	(3,482)	[9]	(3,328)	[10]
Segment core earnings before income taxes	(380)		(1,448)
Income tax expense	785		493
Segment core earnings before preferred stock dividends and attibution of income to non-controlling interest - preferred stock dividends	405		(955)
Preferred Stock Dividends, Income Statement Impact	(3,295)		(3,295)
Less: Net loss attributable to non-controlling interest	15		28
Segment core earnings	(2,875)		(4,222)
Segment Reporting Information, Additional Information [Abstract]
Assets	2,808,355		4,318,387
Segment Reconciling Items [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	0		0
Less: reconciling adjustments(1)(2)(3)	4,205	[1],[2],[3]	3,691	[4],[5],[6]
Net Effective Spread	4,205		3,691
Guarantee and commitment fees	(1,472)	[3]	(1,043)	[6]
Other income/(expense)(3)(4)	1,896	[2],[7]	(5,815)	[5],[8]
Non-interest income/(loss)	424		(6,858)
Provision for loan losses	0		0
Provision for losses	0		0
Noninterest Expense, Excluding Loan, Lease and Other Losses	0		0
Non-interest expense	0	[9]	0	[10]
Segment core earnings before income taxes	4,629	[11]	(3,167)	[12]
Income tax expense	(1,621)		1,109
Segment core earnings before preferred stock dividends and attibution of income to non-controlling interest - preferred stock dividends	3,008	[11]	(2,058)	[12]
Preferred Stock Dividends, Income Statement Impact	0		0
Less: Net loss attributable to non-controlling interest	0		0
Segment core earnings	3,008	[11]	(2,058)	[12]
Segment Reporting Information, Additional Information [Abstract]
Assets	0		0
On and Off Balance Sheet Program Assets, At Principal Balance	$ 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] 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 are considered to be a partial settlement of the respective derivatives contracts rather than as pledged collateral, and accounted for as realized gains and losses. See Note 4 for more information about this rule change. Farmer Mac believes that even though these variation margin amounts are now 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 exchange of variation margin, whether considered a partial settlement of or the pledge of collateral under a derivatives contract, is 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 includes 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.

[8] 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.

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

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

[11] 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.

[12] 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.