Business Segment Reporting - Core Earnings - Business Segments (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income		$ 34,358	$ 31,864	$ 67,998	$ 62,653
Less: reconciling adjustments(1)(2)(3)		0	0	0	0
Net Effective Spread		0	0	0
Guarantee and commitment fees		3,655	3,388	7,281	6,765
Other income/(expense)(3)(4)	[1]	(3,889)	14,819	(10,221)	11,917
Non-interest (loss)/income		(234)	18,207	(2,940)	18,682
Provision for loan losses		(364)	(110)	(413)	(186)
Provision for losses		(94)	(1,146)	(108)	(374)
Noninterest Expense, Excluding Loan, Lease and Other Losses		(9,980)	(9,707)	(19,932)	(18,822)
Non-interest expense	[2]	(10,074)	(10,853)	(20,040)	(19,196)
Income before income taxes		23,686	39,108	44,605	61,953
Income tax expense		(8,400)	(13,769)	(15,735)	(18,000)
Net income		15,286	25,339	28,870	43,953
Preferred Stock Dividends, Income Statement Impact		(3,296)	(3,296)	(6,591)	(6,591)
Less: Net loss/(income) attributable to non-controlling interest		16	119	44	(5,235)
Loss on retirement of preferred stock		0	0	0	(8,147)
Net Income (Loss) Available to Common Stockholders, Basic		12,006	22,162	22,323	23,980
Segment Reporting Information, Additional Information [Abstract]
Assets		16,823,190	15,144,597	16,823,190	15,144,597	$ 15,540,354
On and Off Balance Sheet Program Assets, At Principal Balance		17,116,536	15,130,127	17,116,536	15,130,127
Farm & Ranch [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income		11,606	10,757	22,733	21,988
Less: reconciling adjustments(1)(2)(3)		(1,731)	(1,076)	(3,397)	(2,193)
Net Effective Spread		9,875	9,681	19,336	19,795
Guarantee and commitment fees		3,965	3,693	7,874	7,326
Other income/(expense)(3)(4)	[1]	78	160	175	247
Non-interest (loss)/income		4,043	3,853	8,049	7,573
Provision for loan losses		(364)	(110)	(413)	(186)
Provision for losses		(94)	(1,146)	(108)	(374)
Noninterest Expense, Excluding Loan, Lease and Other Losses		(4,112)	(4,304)	(8,273)	(8,630)
Non-interest expense	[2]	(4,206)	(5,450)	(8,381)	(9,004)
Segment core earnings before income taxes		9,348	7,974	18,591	18,178
Income tax expense		(3,272)	(2,791)	(6,508)	(6,362)
Segment core earnings before preferred stock dividends and attibution of income to non-controlling interest - preferred stock dividends		6,076	5,183	12,083	11,816
Preferred Stock Dividends, Income Statement Impact		0	0	0	0
Less: Net loss/(income) attributable to non-controlling interest		0	0	0	0
Loss on retirement of preferred stock					0
Segment core earnings		6,076	5,183	12,083	11,816
Segment Reporting Information, Additional Information [Abstract]
Assets		3,311,270	2,780,018	3,311,270	2,780,018
On and Off Balance Sheet Program Assets, At Principal Balance		5,830,533	5,485,570	5,830,533	5,485,570
USDA Guarantees [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income		4,938	4,643	9,990	8,987
Less: reconciling adjustments(1)(2)(3)		(350)	(177)	(1,094)	(296)
Net Effective Spread		4,588	4,466	8,896	8,691
Guarantee and commitment fees		14	8	21	2
Other income/(expense)(3)(4)	[1]	25	28	83	87
Non-interest (loss)/income		39	36	104	89
Provision for loan losses		0	0	0	0
Provision for losses		0	0	0	0
Noninterest Expense, Excluding Loan, Lease and Other Losses		(1,092)	(1,025)	(2,185)	(1,410)
Non-interest expense	[2]	(1,092)	(1,025)	(2,185)	(1,410)
Segment core earnings before income taxes		3,535	3,477	6,815	7,370
Income tax expense		(1,237)	(1,216)	(2,385)	(2,579)
Segment core earnings before preferred stock dividends and attibution of income to non-controlling interest - preferred stock dividends		2,298	2,261	4,430	4,791
Preferred Stock Dividends, Income Statement Impact		0	0	0	0
Less: Net loss/(income) attributable to non-controlling interest		0	0	0	0
Loss on retirement of preferred stock					0
Segment core earnings		2,298	2,261	4,430	4,791
Segment Reporting Information, Additional Information [Abstract]
Assets		2,046,516	1,913,390	2,046,516	1,913,390
On and Off Balance Sheet Program Assets, At Principal Balance		1,960,358	1,862,430	1,960,358	1,862,430
Rural Utilities [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income		2,855	3,153	5,719	5,611
Less: reconciling adjustments(1)(2)(3)		(293)	(315)	(619)	31
Net Effective Spread		2,562	2,838	5,100	5,642
Guarantee and commitment fees		373	0	668	0
Other income/(expense)(3)(4)	[1]	0	0	0	0
Non-interest (loss)/income		373	0	668	0
Provision for loan losses		0	0	0	0
Provision for losses		0	0	0	0
Noninterest Expense, Excluding Loan, Lease and Other Losses		(830)	(860)	(1,661)	(1,726)
Non-interest expense	[2]	(830)	(860)	(1,661)	(1,726)
Segment core earnings before income taxes		2,105	1,978	4,107	3,916
Income tax expense		(737)	(691)	(1,438)	(1,369)
Segment core earnings before preferred stock dividends and attibution of income to non-controlling interest - preferred stock dividends		1,368	1,287	2,669	2,547
Preferred Stock Dividends, Income Statement Impact		0	0	0	0
Less: Net loss/(income) attributable to non-controlling interest		0	0	0	0
Loss on retirement of preferred stock					0
Segment core earnings		1,368	1,287	2,669	2,547
Segment Reporting Information, Additional Information [Abstract]
Assets		1,023,630	962,702	1,023,630	962,702
On and Off Balance Sheet Program Assets, At Principal Balance		1,934,473	954,188	1,934,473	954,188
Institutional Credit [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income		12,109	11,312	23,858	22,304
Less: reconciling adjustments(1)(2)(3)		(702)	(452)	(1,361)	(1,019)
Net Effective Spread		11,407	10,860	22,497	21,285
Guarantee and commitment fees		458	384	916	769
Other income/(expense)(3)(4)	[1]	0	0	0	0
Non-interest (loss)/income		458	384	916	769
Provision for loan losses		0	0	0	0
Provision for losses		0	0	0	0
Noninterest Expense, Excluding Loan, Lease and Other Losses		(538)	(532)	(1,077)	(1,067)
Non-interest expense	[2]	(538)	(532)	(1,077)	(1,067)
Segment core earnings before income taxes		11,327	10,712	22,336	20,987
Income tax expense		(3,964)	(3,749)	(7,816)	(7,345)
Segment core earnings before preferred stock dividends and attibution of income to non-controlling interest - preferred stock dividends		7,363	6,963	14,520	13,642
Preferred Stock Dividends, Income Statement Impact		0	0	0	0
Less: Net loss/(income) attributable to non-controlling interest		0	0	0	0
Loss on retirement of preferred stock					0
Segment core earnings		7,363	6,963	14,520	13,642
Segment Reporting Information, Additional Information [Abstract]
Assets		6,071,924	5,874,088	6,071,924	5,874,088
On and Off Balance Sheet Program Assets, At Principal Balance		7,391,172	6,827,939	7,391,172	6,827,939
Corporate Segment [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income		2,850	1,999	5,698	3,763
Less: reconciling adjustments(1)(2)(3)		(256)	(57)	(552)	(132)
Net Effective Spread		2,594	1,942	5,146	3,631
Guarantee and commitment fees		0	0	0	0
Other income/(expense)(3)(4)	[1]	(228)	(212)	(900)	(764)
Non-interest (loss)/income		(228)	(212)	(900)	(764)
Provision for loan losses		0	0	0	0
Provision for losses		0	0	0	0
Noninterest Expense, Excluding Loan, Lease and Other Losses		(3,408)	(2,986)	(6,736)	(5,989)
Non-interest expense	[2]	(3,408)	(2,986)	(6,736)	(5,989)
Segment core earnings before income taxes		(1,042)	(1,256)	(2,490)	(3,122)
Income tax expense		254	356	747	2,872
Segment core earnings before preferred stock dividends and attibution of income to non-controlling interest - preferred stock dividends		(788)	(900)	(1,743)	(250)
Preferred Stock Dividends, Income Statement Impact		(3,296)	(3,296)	(6,591)	(6,591)
Less: Net loss/(income) attributable to non-controlling interest		16	119	44	(5,235)
Loss on retirement of preferred stock					0
Segment core earnings		(4,068)	(4,077)	(8,290)	(12,076)
Segment Reporting Information, Additional Information [Abstract]
Assets		4,369,850	3,614,399	4,369,850	3,614,399
Segment Reconciling Items [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income		0	0	0	0
Less: reconciling adjustments(1)(2)(3)		3,332	2,077	7,023	3,609
Net Effective Spread		3,332	2,077	7,023	3,609
Guarantee and commitment fees		(1,155)	(697)	(2,198)	(1,332)
Other income/(expense)(3)(4)	[1]	(3,764)	14,843	(9,579)	12,347
Non-interest (loss)/income		(4,919)	14,146	(11,777)	11,015
Provision for loan losses		0	0	0	0
Provision for losses		0	0	0	0
Noninterest Expense, Excluding Loan, Lease and Other Losses		0	0	0	0
Non-interest expense	[2]	0	0	0	0
Segment core earnings before income taxes	[3]	(1,587)	16,223	(4,754)	14,624
Income tax expense		556	(5,678)	1,665	(3,217)
Segment core earnings before preferred stock dividends and attibution of income to non-controlling interest - preferred stock dividends	[3]	(1,031)	10,545	(3,089)	11,407
Preferred Stock Dividends, Income Statement Impact		0	0	0	0
Less: Net loss/(income) attributable to non-controlling interest		0	0	0	0
Loss on retirement of preferred stock					(8,147)
Segment core earnings	[3]	(1,031)	10,545	(3,089)	3,260
Segment Reporting Information, Additional Information [Abstract]
Assets		0	0	0	0
On and Off Balance Sheet Program Assets, At Principal Balance		$ 0	$ 0	$ 0	$ 0

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

[2] (4) 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.

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