Fair Value Disclosures - Summary of Carrying Value and Fair Value (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	$ 870,040	$ 817,046
Loans	2,589,006	2,971,187
Financial derivatives, Assets	36,190	40,250
Notes payable - Due within one year	6,775,228	6,091,573
Notes payable - Due after one year	4,898,122	4,288,670
Debt securities of consolidated trusts held by third parties	170,462	726,826
Financial derivatives, Liabilities	164,949	160,024
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	870,040	817,046
Loans	2,549,535	2,894,156
Financial derivatives, Assets	36,190	40,250
Notes payable - Due within one year	6,775,226	6,087,879
Notes payable - Due after one year	4,700,680	4,104,882
Debt securities of consolidated trusts held by third parties	163,909	701,583
Financial derivatives, Liabilities	164,949	160,024
Investment Securities | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable Securities	2,636,328	2,184,490
Investment Securities | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable Securities	2,636,328	2,184,490
Farmer Mac Guaranteed Securities | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Guarantee and commitment fees receivable	20,731	17,960
Farmer Mac Guaranteed Securities | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Guarantee and commitment fees receivable	19,279	15,498
LTSPCs | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Guarantee and commitment fees receivable	23,769	22,802
LTSPCs | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Guarantee and commitment fees receivable	18,461	15,886
LTSPCs | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Guarantee and commitment obligations	22,947	22,047
LTSPCs | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Guarantee and commitment obligations	17,639	15,131
Farmer Mac Guaranteed Securities | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Guarantee and commitment obligations	18,206	14,771
Farmer Mac Guaranteed Securities | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Guarantee and commitment obligations	16,754	12,309
Farmer Mac Guarantee | Farmer Mac Guaranteed Securities | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable Securities	4,648,507	4,289,272
Farmer Mac Guarantee | Farmer Mac Guaranteed Securities | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable Securities	4,648,507	4,289,272
USDA Guarantee | USDA Guaranteed Securities | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable Securities	1,590,628	1,491,905
USDA Guarantee | USDA Guaranteed Securities | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable Securities	$ 1,590,628	$ 1,491,905