Fair Value Disclosures - Summary of Carrying Value and Fair Value (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative Assets	$ 21,806	$ 29,523
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	650,723	785,564
Loans	2,936,726	2,746,742
Derivative Assets	23,164	31,173
Notes payable - Due within one year	6,781,622	6,573,013
Notes payable - Due after one year	5,228,932	5,202,751
Debt securities of consolidated trusts held by third parties	167,892	164,910
Financial derivatives, Liabilities	99,063	150,682
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	650,723	785,564
Loans	2,949,165	2,729,774
Derivative Assets	23,164	31,173
Notes payable - Due within one year	6,785,164	6,567,366
Notes payable - Due after one year	5,173,667	5,034,739
Debt securities of consolidated trusts held by third parties	168,488	167,621
Financial derivatives, Liabilities	99,063	150,682
Investment Securities [Member] | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable Securities	2,456,916	2,499,629
Investment Securities [Member] | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable Securities	2,456,916	2,499,629
Farmer Mac Guaranteed Securities [Member] | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Guarantee and commitment fees receivable	19,385	20,432
Farmer Mac Guaranteed Securities [Member] | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Guarantee and commitment fees receivable	17,670	18,926
Long-Term Standby Purchase Commitments [Member] | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Guarantee and commitment fees receivable	31,621	27,805
Long-Term Standby Purchase Commitments [Member] | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Guarantee and commitment fees receivable	25,404	22,863
Long-Term Standby Purchase Commitments [Member] | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Guarantee and commitment obligations	30,722	26,896
Long-Term Standby Purchase Commitments [Member] | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Guarantee and commitment obligations	24,504	21,954
Farmer Mac Guaranteed Securities [Member] | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Guarantee and commitment obligations	16,240	17,354
Farmer Mac Guaranteed Securities [Member] | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Guarantee and commitment obligations	14,523	15,849
Farmer Mac Guarantee | Farmer Mac Guaranteed Securities [Member] | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable Securities	5,058,853	4,766,258
Farmer Mac Guarantee | Farmer Mac Guaranteed Securities [Member] | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable Securities	5,058,853	4,766,258
USDA Guarantee | USDA Guaranteed Securities [Member] | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable Securities	1,617,356	1,590,783
USDA Guarantee | USDA Guaranteed Securities [Member] | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable Securities	$ 1,617,356	$ 1,590,783