Fair Value Disclosures - Summary of Carrying Value and Fair Value (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	$ 785,564	$ 817,046
Loans	2,746,742	2,971,187
Financial derivatives, Assets	31,173	40,250
Notes payable - Due within one year	6,573,013	6,091,573
Notes payable - Due after one year	5,202,751	4,288,670
Debt securities of consolidated trusts held by third parties	164,910	726,826
Financial derivatives, Liabilities	150,682	160,024
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	785,564	817,046
Loans	2,729,774	2,894,156
Financial derivatives, Assets	31,173	40,250
Notes payable - Due within one year	6,567,366	6,087,879
Notes payable - Due after one year	5,034,739	4,104,882
Debt securities of consolidated trusts held by third parties	167,621	701,583
Financial derivatives, Liabilities	150,682	160,024
Investment Securities [Member] | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable Securities	2,499,629	2,184,490
Investment Securities [Member] | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable Securities	2,499,629	2,184,490
Farmer Mac Guaranteed Securities [Member] | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Guarantee and commitment fees receivable	20,432	17,960
Farmer Mac Guaranteed Securities [Member] | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Guarantee and commitment fees receivable	18,926	15,498
Long-Term Standby Purchase Commitments [Member] | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Guarantee and commitment fees receivable	27,805	22,802
Long-Term Standby Purchase Commitments [Member] | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Guarantee and commitment fees receivable	22,863	15,886
Long-Term Standby Purchase Commitments [Member] | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Guarantee and commitment obligations	26,896	22,047
Long-Term Standby Purchase Commitments [Member] | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Guarantee and commitment obligations	21,954	15,131
Farmer Mac Guaranteed Securities [Member] | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Guarantee and commitment obligations	17,354	14,771
Farmer Mac Guaranteed Securities [Member] | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Guarantee and commitment obligations	15,849	12,309
Farmer Mac Guarantee | Farmer Mac Guaranteed Securities [Member] | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable Securities	4,766,258	4,289,272
Farmer Mac Guarantee | Farmer Mac Guaranteed Securities [Member] | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable Securities	4,766,258	4,289,272
USDA Guarantee | USDA Guaranteed Securities [Member] | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable Securities	1,590,783	1,491,905
USDA Guarantee | USDA Guaranteed Securities [Member] | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable Securities	$ 1,590,783	$ 1,491,905