Fair Value Disclosures - Summary of Carrying Value and Fair Value (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative Assets	$ 18,934	$ 29,523
Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	651,713	785,564
Loans	2,979,997	2,746,742
Derivative Assets	19,676	31,173
Notes payable - Due within one year	7,046,567	6,573,013
Notes payable - Due after one year	5,051,897	5,202,751
Debt securities of consolidated trusts held by third parties	180,157	164,910
Financial derivatives, Liabilities	91,445	150,682
Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	651,713	785,564
Loans	2,992,638	2,729,774
Derivative Assets	19,676	31,173
Notes payable - Due within one year	7,021,678	6,567,366
Notes payable - Due after one year	5,037,035	5,034,739
Debt securities of consolidated trusts held by third parties	178,076	167,621
Financial derivatives, Liabilities	91,445	150,682
Investment Securities [Member] | Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable Securities	2,503,112	2,499,629
Investment Securities [Member] | Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable Securities	2,503,112	2,499,629
Farmer Mac Guaranteed Securities [Member] | Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Guarantee and commitment fees receivable	18,291	20,432
Farmer Mac Guaranteed Securities [Member] | Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Guarantee and commitment fees receivable	16,480	18,926
Long-Term Standby Purchase Commitments [Member] | Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Guarantee and commitment fees receivable	33,414	27,805
Long-Term Standby Purchase Commitments [Member] | Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Guarantee and commitment fees receivable	27,016	22,863
Long-Term Standby Purchase Commitments [Member] | Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Guarantee and commitment obligations	32,471	26,896
Long-Term Standby Purchase Commitments [Member] | Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Guarantee and commitment obligations	26,073	21,954
Farmer Mac Guaranteed Securities [Member] | Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Guarantee and commitment obligations	15,845	17,354
Farmer Mac Guaranteed Securities [Member] | Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Guarantee and commitment obligations	14,033	15,849
Farmer Mac Guarantee [Member] | Farmer Mac Guaranteed Securities [Member] | Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable Securities	5,138,756	4,766,258
Farmer Mac Guarantee [Member] | Farmer Mac Guaranteed Securities [Member] | Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable Securities	5,138,756	4,766,258
USDA Guarantee [Member] | USDA Guaranteed Securities [Member] | Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable Securities	1,629,010	1,590,783
USDA Guarantee [Member] | USDA Guaranteed Securities [Member] | Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable Securities	$ 1,629,010	$ 1,590,783