Business Segment Reporting - (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012		Dec. 31, 2012
Segment Reporting Information [Line Items]
Total interest income	$ 62,975	[1]	$ 63,810	[2]	$ 186,218	[1]	$ 208,519	[2]
Interest income related to consolidated trusts owned by third parties reclassified to guarantee fee income	0		0		0		0
Interest Expense	(34,787)	[3]	(33,448)	[4]	(101,499)	[3]	(109,332)	[4]
Net interest income	28,188		30,362		84,719		99,187
Guaranty Fee Income	6,819		6,401		20,190		18,395
Other Non-Interest Income (Expense), Excluding Guarantee and Commitment Fees	3,002	[5]	2,063	[6]	28,559	[5]	(23,034)	[6]
Noninterest Income/(loss)	9,821		8,464		48,749		(4,639)
Provision for loan losses	(499)		137		(598)		(663)
Provision for Other Credit Losses	463		(43)		1,034		1,381
Noninterest Expense, Excluding Loan, Lease and Other Losses	7,978		7,791		24,452		23,418
Noninterest Expense	8,441	[7]	7,748	[7]	25,486	[7]	24,799	[7]
Income/(loss) before income taxes	30,067		30,941		108,580		70,412
Income tax (benefit)/expense	(8,226)		(8,294)		(29,978)		(17,319)
Net income	21,841		22,647		78,602		53,093
Preferred stock dividends	(881)		(719)		(2,613)		(2,159)
Net Income Attributable to Noncontrolling Interest - preferred stock dividends	(5,547)		(5,547)		(16,641)		(16,641)
Net income attributable to common stockholders	15,413		16,381		59,348		34,293
Total assets at carrying value	13,085,007		12,502,481		13,085,007		12,502,481		12,622,201
On and Off Balance Sheet Program Assets, At Principal Balance	13,786,266		12,468,059		13,786,266		12,468,059
Farm & Ranch [Member]
Segment Reporting Information [Line Items]
Segment interest and dividend income operating	30,139	[1]	28,887	[2]	88,318	[1]	103,328	[2]
Interest income related to consolidated trusts owned by third parties reclassified to guarantee fee income	(227)		(190)		(602)		(1,463)
Segment interest expense	(13,738)	[3]	(11,858)	[4]	(39,168)	[3]	(53,403)	[4]
Segment net effective spread	16,174		16,839		48,548		48,462
Segment guarantee fee income	5,953		5,551		17,613		16,340
Other Non-Interest Income (Expense), Excluding Guarantee and Commitment Fees	157	[5]	519	[6]	2,051	[5]	1,470	[6]
Segment non interest income	6,110		6,070		19,664		17,810
Provision for loan losses	(499)		137		(598)		(663)
Provision for Other Credit Losses	463		(43)		1,034		1,381
Noninterest Expense, Excluding Loan, Lease and Other Losses	3,785		3,582		11,756		10,650
Noninterest Expense	4,248	[7]	3,539	[7]	12,790	[7]	12,031	[7]
Segment core earnings before income taxes	18,535		19,233		56,020		54,904
Income tax (benefit)/expense	(6,487)		(6,731)		(19,607)		(19,216)
Segment core earnings before preferred stock dividends and attribution of income to non-controlling interest - preferred stock dividends	12,048		12,502		36,413		35,688
Preferred stock dividends	0		0		0		0
Net Income Attributable to Noncontrolling Interest - preferred stock dividends	0		0		0		0
Segment core earnings	12,048		12,502		36,413		35,688
Total assets at carrying value	5,630,252		5,046,716		5,630,252		5,046,716
On and Off Balance Sheet Program Assets, At Principal Balance	9,545,398		8,712,157		9,545,398		8,712,157
USDA Guarantees [Member]
Segment Reporting Information [Line Items]
Segment interest and dividend income operating	13,461	[1]	14,299	[2]	39,959	[1]	42,811	[2]
Interest income related to consolidated trusts owned by third parties reclassified to guarantee fee income	0		0		0		0
Segment interest expense	(10,630)	[3]	(11,469)	[4]	(31,457)	[3]	(34,425)	[4]
Segment net effective spread	2,831		2,830		8,502		8,386
Segment guarantee fee income	30		38		105		126
Other Non-Interest Income (Expense), Excluding Guarantee and Commitment Fees	241	[5]	251	[6]	758	[5]	525	[6]
Segment non interest income	271		289		863		651
Provision for loan losses	0		0		0		0
Provision for Other Credit Losses	0		0		0		0
Noninterest Expense, Excluding Loan, Lease and Other Losses	769		757		2,341		2,265
Noninterest Expense	769	[7]	757	[7]	2,341	[7]	2,265	[7]
Segment core earnings before income taxes	2,333		2,362		7,024		6,772
Income tax (benefit)/expense	(817)		(827)		(2,459)		(2,371)
Segment core earnings before preferred stock dividends and attribution of income to non-controlling interest - preferred stock dividends	1,516		1,535		4,565		4,401
Preferred stock dividends	0		0		0		0
Net Income Attributable to Noncontrolling Interest - preferred stock dividends	0		0		0		0
Segment core earnings	1,516		1,535		4,565		4,401
Total assets at carrying value	1,674,309		1,640,940		1,674,309		1,640,940
On and Off Balance Sheet Program Assets, At Principal Balance	1,676,793		1,599,226		1,676,793		1,599,226
Rural Utilities [Member]
Segment Reporting Information [Line Items]
Segment interest and dividend income operating	14,958	[1]	15,401	[2]	44,838	[1]	48,223	[2]
Interest income related to consolidated trusts owned by third parties reclassified to guarantee fee income	0		0		0		0
Segment interest expense	(11,973)	[3]	(12,292)	[4]	(35,806)	[3]	(38,931)	[4]
Segment net effective spread	2,985		3,109		9,032		9,292
Segment guarantee fee income	1,063		1,002		3,074		3,392
Other Non-Interest Income (Expense), Excluding Guarantee and Commitment Fees	0	[5]	300	[6]	0	[5]	301	[6]
Segment non interest income	1,063		1,302		3,074		3,693
Provision for loan losses	0		0		0		0
Provision for Other Credit Losses	0		0		0		0
Noninterest Expense, Excluding Loan, Lease and Other Losses	1,356		1,368		4,104		4,135
Noninterest Expense	1,356	[7]	1,368	[7]	4,104	[7]	4,135	[7]
Segment core earnings before income taxes	2,692		3,043		8,002		8,850
Income tax (benefit)/expense	(942)		(1,065)		(2,801)		(3,097)
Segment core earnings before preferred stock dividends and attribution of income to non-controlling interest - preferred stock dividends	1,750		1,978		5,201		5,753
Preferred stock dividends	0		0		0		0
Net Income Attributable to Noncontrolling Interest - preferred stock dividends	0		0		0		0
Segment core earnings	1,750		1,978		5,201		5,753
Total assets at carrying value	2,567,828		2,206,529		2,567,828		2,206,529
On and Off Balance Sheet Program Assets, At Principal Balance	2,564,075		2,156,676		2,564,075		2,156,676
Corporate [Member]
Segment Reporting Information [Line Items]
Segment interest and dividend income operating	5,263	[1]	6,437	[2]	16,468	[1]	18,693	[2]
Interest income related to consolidated trusts owned by third parties reclassified to guarantee fee income	0		0		0		0
Segment interest expense	(1,472)	[3]	(1,959)	[4]	(4,443)	[3]	(4,736)	[4]
Segment net effective spread	3,791		4,478		12,025		13,957
Segment guarantee fee income	0		0		0		0
Other Non-Interest Income (Expense), Excluding Guarantee and Commitment Fees	(825)	[5]	(699)	[6]	1,395	[5]	(1,939)	[6]
Segment non interest income	(825)		(699)		1,395		(1,939)
Provision for loan losses	0		0		0		0
Provision for Other Credit Losses	0		0		0		0
Noninterest Expense, Excluding Loan, Lease and Other Losses	2,068		2,084		6,251		6,368
Noninterest Expense	2,068	[7]	2,084	[7]	6,251	[7]	6,368	[7]
Segment core earnings before income taxes	898		1,695		7,169		5,650
Income tax (benefit)/expense	1,983		1,941		5,516		5,347
Segment core earnings before preferred stock dividends and attribution of income to non-controlling interest - preferred stock dividends	2,881		3,636		12,685		10,997
Preferred stock dividends	(881)		(719)		(2,613)		(2,159)
Net Income Attributable to Noncontrolling Interest - preferred stock dividends	(5,547)		(5,547)		(16,641)		(16,641)
Segment core earnings	(3,547)		(2,630)		(6,569)		(7,803)
Total assets at carrying value	3,212,618		3,608,296		3,212,618		3,608,296
On and Off Balance Sheet Program Assets, At Principal Balance	0		0		0		0
Reconciling Adjustments [Member]
Segment Reporting Information [Line Items]
Segment interest and dividend income operating	(846)	[1]	(1,214)	[2]	(3,365)	[1]	(4,536)	[2]
Interest income related to consolidated trusts owned by third parties reclassified to guarantee fee income	227		190		602		1,463
Segment interest expense	3,026	[3]	4,130	[4]	9,375	[3]	22,163	[4]
Segment net effective spread	2,407		3,106		6,612		19,090
Segment guarantee fee income	(227)		(190)		(602)		(1,463)
Other Non-Interest Income (Expense), Excluding Guarantee and Commitment Fees	3,429	[5]	1,692	[6]	24,355	[5]	(23,391)	[6]
Segment non interest income	3,202		1,502		23,753		(24,854)
Provision for loan losses	0		0		0		0
Provision for Other Credit Losses	0		0		0		0
Noninterest Expense, Excluding Loan, Lease and Other Losses	0		0		0		0
Noninterest Expense	0	[7]	0	[7]	0	[7]	0	[7]
Segment core earnings before income taxes	5,609	[8]	4,608	[8]	30,365	[8]	(5,764)	[8]
Income tax (benefit)/expense	(1,963)		(1,612)		(10,627)		2,018
Segment core earnings before preferred stock dividends and attribution of income to non-controlling interest - preferred stock dividends	3,646	[8]	2,996	[8]	19,738	[8]	(3,746)	[8]
Preferred stock dividends	0		0		0		0
Net Income Attributable to Noncontrolling Interest - preferred stock dividends	0		0		0		0
Segment core earnings	3,646	[8]	2,996	[8]	19,738	[8]	(3,746)	[8]
Total assets at carrying value	0		0		0		0
On and Off Balance Sheet Program Assets, At Principal Balance	$ 0		$ 0		$ 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 yield maintenance income and amortization of premiums 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 "Gains/(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, which are included in "Gains/(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 Guaranteed Securities.

[6] Includes reconciling adjustments for the reclassification of yield maintenance income, expenses related to interest rate swaps 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 Guaranteed Securities.

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

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