Business Segment Reporting - Core Earnings - Business Segments (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income		$ 35,563	$ 32,183	$ 103,561	$ 94,836
Less: reconciling adjustments(1)(2)(3)		0	0	0	0
Net Effective Spread		0	0	0
Guarantee and commitment fees		3,798	3,532	11,079	10,297
Other income/(expense)(3)(4)	[1]	303	(8,513)	(9,918)	3,404
Non-interest income/(loss)		4,101	(4,981)	1,161	13,701
(Provision for)/release of loan losses		(191)	1,164	(604)	978
Provision for losses		222	(861)	114	(1,235)
Noninterest Expense, Excluding Loan, Lease and Other Losses		(9,525)	(9,560)	(29,457)	(28,382)
Non-interest expense	[2]	(9,303)	(10,421)	(29,343)	(29,617)
Income before income taxes		30,170	17,945	74,775	79,898
Income tax expense		(10,529)	(6,327)	(26,264)	(24,327)
Net income		19,641	11,618	48,511	55,571
Preferred Stock Dividends, Income Statement Impact		(3,295)	(3,295)	(9,886)	(9,886)
Less: Net loss/(income) attributable to non-controlling interest		18	36	62	(5,199)
Loss on retirement of preferred stock		0	0	0	(8,147)
Net Income (Loss) Available to Common Stockholders, Basic		16,364	8,359	38,687	32,339
Segment Reporting Information, Additional Information [Abstract]
Assets		16,000,905	14,853,845	16,000,905	14,853,845	$ 15,540,354
On and Off Balance Sheet Program Assets, At Principal Balance		17,247,739	15,627,979	17,247,739	15,627,979
Farm & Ranch [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income		12,039	10,838	34,772	32,825
Less: reconciling adjustments(1)(2)(3)		(1,336)	(1,210)	(4,733)	(3,402)
Net Effective Spread		10,703	9,628	30,039	29,423
Guarantee and commitment fees		3,516	3,785	11,390	11,111
Other income/(expense)(3)(4)	[1]	276	513	451	760
Non-interest income/(loss)		3,792	4,298	11,841	11,871
(Provision for)/release of loan losses		(191)	1,164	(604)	978
Provision for losses		222	(861)	114	(1,235)
Noninterest Expense, Excluding Loan, Lease and Other Losses		(3,673)	(4,228)	(11,946)	(12,858)
Non-interest expense	[2]	(3,451)	(5,089)	(11,832)	(14,093)
Segment core earnings before income taxes		10,853	10,001	29,444	28,179
Income tax expense		(3,799)	(3,500)	(10,307)	(9,862)
Segment core earnings before preferred stock dividends and attibution of income to non-controlling interest - preferred stock dividends		7,054	6,501	19,137	18,317
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		7,054	6,501	19,137	18,317
Segment Reporting Information, Additional Information [Abstract]
Assets		3,436,641	2,856,097	3,436,641	2,856,097
On and Off Balance Sheet Program Assets, At Principal Balance		6,004,728	5,504,030	6,004,728	5,504,030
USDA Guarantees [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income		5,753	4,515	15,743	13,503
Less: reconciling adjustments(1)(2)(3)		(564)	115	(1,658)	(182)
Net Effective Spread		5,189	4,630	14,085	13,321
Guarantee and commitment fees		29	7	50	9
Other income/(expense)(3)(4)	[1]	95	13	178	100
Non-interest income/(loss)		124	20	228	109
(Provision for)/release of loan losses		0	0	0	0
Provision for losses		0	0	0	0
Noninterest Expense, Excluding Loan, Lease and Other Losses		(933)	(986)	(3,118)	(2,396)
Non-interest expense	[2]	(933)	(986)	(3,118)	(2,396)
Segment core earnings before income taxes		4,380	3,664	11,195	11,034
Income tax expense		(1,533)	(1,282)	(3,918)	(3,861)
Segment core earnings before preferred stock dividends and attibution of income to non-controlling interest - preferred stock dividends		2,847	2,382	7,277	7,173
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		2,847	2,382	7,277	7,173
Segment Reporting Information, Additional Information [Abstract]
Assets		2,062,195	1,941,166	2,062,195	1,941,166
On and Off Balance Sheet Program Assets, At Principal Balance		2,020,834	1,898,625	2,020,834	1,898,625
Rural Utilities [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income		2,963	3,130	8,682	8,741
Less: reconciling adjustments(1)(2)(3)		(320)	(223)	(939)	(192)
Net Effective Spread		2,643	2,907	7,743	8,549
Guarantee and commitment fees		529	100	1,197	100
Other income/(expense)(3)(4)	[1]	0	0	0	0
Non-interest income/(loss)		529	100	1,197	100
(Provision for)/release of loan losses		0	0	0	0
Provision for losses		0	0	0	0
Noninterest Expense, Excluding Loan, Lease and Other Losses		(553)	(838)	(2,214)	(2,564)
Non-interest expense	[2]	(553)	(838)	(2,214)	(2,564)
Segment core earnings before income taxes		2,619	2,169	6,726	6,085
Income tax expense		(917)	(760)	(2,355)	(2,129)
Segment core earnings before preferred stock dividends and attibution of income to non-controlling interest - preferred stock dividends		1,702	1,409	4,371	3,956
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		1,702	1,409	4,371	3,956
Segment Reporting Information, Additional Information [Abstract]
Assets		1,008,903	987,115	1,008,903	987,115
On and Off Balance Sheet Program Assets, At Principal Balance		1,867,666	1,500,307	1,867,666	1,500,307
Institutional Credit [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income		12,226	11,686	36,084	33,990
Less: reconciling adjustments(1)(2)(3)		(799)	(415)	(2,160)	(1,434)
Net Effective Spread		11,427	11,271	33,924	32,556
Guarantee and commitment fees		459	436	1,375	1,205
Other income/(expense)(3)(4)	[1]	0	0	0	0
Non-interest income/(loss)		459	436	1,375	1,205
(Provision for)/release of loan losses		0	0	0	0
Provision for losses		0	0	0	0
Noninterest Expense, Excluding Loan, Lease and Other Losses		(1,253)	(522)	(2,330)	(1,589)
Non-interest expense	[2]	(1,253)	(522)	(2,330)	(1,589)
Segment core earnings before income taxes		10,633	11,185	32,969	32,172
Income tax expense		(3,722)	(3,915)	(11,538)	(11,260)
Segment core earnings before preferred stock dividends and attibution of income to non-controlling interest - preferred stock dividends		6,911	7,270	21,431	20,912
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		6,911	7,270	21,431	20,912
Segment Reporting Information, Additional Information [Abstract]
Assets		6,045,227	5,405,360	6,045,227	5,405,360
On and Off Balance Sheet Program Assets, At Principal Balance		7,354,511	6,725,017	7,354,511	6,725,017
Corporate Segment [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income		2,582	2,014	8,280	5,777
Less: reconciling adjustments(1)(2)(3)		(345)	(63)	(897)	(195)
Net Effective Spread		2,237	1,951	7,383	5,582
Guarantee and commitment fees		0	0	0	0
Other income/(expense)(3)(4)	[1]	(388)	(619)	(1,288)	(1,383)
Non-interest income/(loss)		(388)	(619)	(1,288)	(1,383)
(Provision for)/release of loan losses		0	0	0	0
Provision for losses		0	0	0	0
Noninterest Expense, Excluding Loan, Lease and Other Losses		(3,113)	(2,986)	(9,849)	(8,975)
Non-interest expense	[2]	(3,113)	(2,986)	(9,849)	(8,975)
Segment core earnings before income taxes		(1,264)	(1,654)	(3,754)	(4,776)
Income tax expense		474	533	1,221	3,405
Segment core earnings before preferred stock dividends and attibution of income to non-controlling interest - preferred stock dividends		(790)	(1,121)	(2,533)	(1,371)
Preferred Stock Dividends, Income Statement Impact		(3,295)	(3,295)	(9,886)	(9,886)
Less: Net loss/(income) attributable to non-controlling interest		18	36	62	(5,199)
Loss on retirement of preferred stock					0
Segment core earnings		(4,067)	(4,380)	(12,357)	(16,456)
Segment Reporting Information, Additional Information [Abstract]
Assets		3,447,939	3,664,107	3,447,939	3,664,107
Segment Reconciling Items [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income		0	0	0	0
Less: reconciling adjustments(1)(2)(3)		3,364	1,796	10,387	5,405
Net Effective Spread		3,364	1,796	10,387	5,405
Guarantee and commitment fees		(735)	(796)	(2,933)	(2,128)
Other income/(expense)(3)(4)	[1]	320	(8,420)	(9,259)	3,927
Non-interest income/(loss)		(415)	(9,216)	(12,192)	1,799
(Provision for)/release of 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]	2,949	(7,420)	(1,805)	7,204
Income tax expense		(1,032)	2,597	633	(620)
Segment core earnings before preferred stock dividends and attibution of income to non-controlling interest - preferred stock dividends	[3]	1,917	(4,823)	(1,172)	6,584
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]	1,917	(4,823)	(1,172)	(1,563)
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.