Fair Value Disclosures - Quantitative Information (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
Fair Value, Measurements, Recurring [Member] | Indicative Bid Approach Valuation Technique [Member] | Auction-rate certificates backed by Government guaranteed student loans [Member] | Floating Interest Rate [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Available-for-sale securities	$ 65,088	$ 63,159
Fair Value, Measurements, Recurring [Member] | Discounted Cash Flows Approach Valuation Technique [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Financial derivatives, Liabilities	329	691
Fair Value, Measurements, Recurring [Member] | Discounted Cash Flows Approach Valuation Technique [Member] | Asset-backed Securities [Member] | Floating Interest Rate [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Trading securities	977	1,247
Fair Value, Measurements, Recurring [Member] | Discounted Cash Flows Approach Valuation Technique [Member] | Collateralized Mortgage Backed Securities [Member] | Floating Interest Rate [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Available-for-sale securities	214
Farmer Mac Guarantee [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Available-for-sale securities	5,138,756	4,766,258
Farmer Mac Guarantee [Member] | Fair Value, Measurements, Recurring [Member] | Discounted Cash Flows Approach Valuation Technique [Member] | Farm & Ranch Guaranteed Securities [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Available-for-sale securities	3,598,523	3,426,489
Farmer Mac Guarantee [Member] | Fair Value, Measurements, Recurring [Member] | Discounted Cash Flows Approach Valuation Technique [Member] | USDA Guarantees - Farmer Mac Guaranteed Securities [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Available-for-sale securities	25,708	26,681
Farmer Mac Guarantee [Member] | Fair Value, Measurements, Recurring [Member] | Discounted Cash Flows Approach Valuation Technique [Member] | Farmer Mac Guaranteed Securities - Rural Utilities [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Available-for-sale securities	1,514,525	1,313,088
USDA Guarantee [Member] | Fair Value, Measurements, Recurring [Member] | Discounted Cash Flows Approach Valuation Technique [Member] | USDA Guaranteed Securities [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Marketable Securities	1,629,010	1,590,783
Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Available-for-sale securities	65,302	63,159
Trading securities	977	1,247
Marketable Securities	66,279	64,406
Financial derivatives, Liabilities	329	691
Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Indicative Bid Approach Valuation Technique [Member] | Minimum [Member] | Auction-rate certificates backed by Government guaranteed student loans [Member] | Floating Interest Rate [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value Inputs, Range of Offered Quotes	82.00%	82.00%
Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Indicative Bid Approach Valuation Technique [Member] | Maximum [Member] | Auction-rate certificates backed by Government guaranteed student loans [Member] | Floating Interest Rate [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value Inputs, Range of Offered Quotes	92.00%	90.00%
Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Indicative Bid Approach Valuation Technique [Member] | Weighted Average [Member] | Auction-rate certificates backed by Government guaranteed student loans [Member] | Floating Interest Rate [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value Inputs, Range of Offered Quotes	87.80%	85.00%
Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Discounted Cash Flows Approach Valuation Technique [Member] | Asset-backed Securities [Member] | Floating Interest Rate [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value Inputs, Constant Prepayment Rate	10.00%	10.00%
Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Discounted Cash Flows Approach Valuation Technique [Member] | Collateralized Mortgage Obligations [Member] | Floating Interest Rate [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value Inputs, Constant Prepayment Rate	6.00%
Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Discounted Cash Flows Approach Valuation Technique [Member] | Minimum [Member] | Derivative Financial Instruments, Liabilities [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value Inputs, discount rate	0.70%	1.00%
Fair Value Inputs, Constant Prepayment Rate	10.00%	11.00%
Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Discounted Cash Flows Approach Valuation Technique [Member] | Minimum [Member] | Asset-backed Securities [Member] | Floating Interest Rate [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value Inputs, discount rate	13.10%	12.40%
Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Discounted Cash Flows Approach Valuation Technique [Member] | Minimum [Member] | Collateralized Mortgage Obligations [Member] | Floating Interest Rate [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value Inputs, discount rate	1.70%
Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Discounted Cash Flows Approach Valuation Technique [Member] | Maximum [Member] | Derivative Financial Instruments, Liabilities [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value Inputs, discount rate	2.30%	3.00%
Fair Value Inputs, Constant Prepayment Rate	14.00%	19.00%
Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Discounted Cash Flows Approach Valuation Technique [Member] | Maximum [Member] | Asset-backed Securities [Member] | Floating Interest Rate [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value Inputs, discount rate	21.50%	19.70%
Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Discounted Cash Flows Approach Valuation Technique [Member] | Maximum [Member] | Collateralized Mortgage Obligations [Member] | Floating Interest Rate [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value Inputs, discount rate	1.70%
Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Discounted Cash Flows Approach Valuation Technique [Member] | Weighted Average [Member] | Derivative Financial Instruments, Liabilities [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value Inputs, discount rate	1.30%	1.70%
Fair Value Inputs, Constant Prepayment Rate	12.00%	16.00%
Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Discounted Cash Flows Approach Valuation Technique [Member] | Weighted Average [Member] | Asset-backed Securities [Member] | Floating Interest Rate [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value Inputs, discount rate	17.40%	16.20%
Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Discounted Cash Flows Approach Valuation Technique [Member] | Weighted Average [Member] | Collateralized Mortgage Obligations [Member] | Floating Interest Rate [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value Inputs, discount rate	1.70%
Level 3 [Member] | Farmer Mac Guarantee [Member] | Fair Value, Measurements, Recurring [Member] | Farmer Mac Guaranteed Securities [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Available-for-sale securities	5,138,756	4,766,258
Level 3 [Member] | Farmer Mac Guarantee [Member] | Fair Value, Measurements, Recurring [Member] | Farm & Ranch Guaranteed Securities [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Available-for-sale securities	3,598,523	3,426,489
Level 3 [Member] | Farmer Mac Guarantee [Member] | Fair Value, Measurements, Recurring [Member] | USDA Guarantees - Farmer Mac Guaranteed Securities [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Available-for-sale securities	25,708	26,681
Level 3 [Member] | Farmer Mac Guarantee [Member] | Fair Value, Measurements, Recurring [Member] | Farmer Mac Guaranteed Securities - Rural Utilities [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Available-for-sale securities	1,514,525	1,313,088
Level 3 [Member] | Farmer Mac Guarantee [Member] | Fair Value, Measurements, Recurring [Member] | Discounted Cash Flows Approach Valuation Technique [Member] | Minimum [Member] | Farm & Ranch Guaranteed Securities [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value Inputs, discount rate	0.90%	1.10%
Level 3 [Member] | Farmer Mac Guarantee [Member] | Fair Value, Measurements, Recurring [Member] | Discounted Cash Flows Approach Valuation Technique [Member] | Minimum [Member] | USDA Guarantees - Farmer Mac Guaranteed Securities [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value Inputs, discount rate	0.80%	1.00%
Fair Value Inputs, Constant Prepayment Rate	8.00%	8.00%
Level 3 [Member] | Farmer Mac Guarantee [Member] | Fair Value, Measurements, Recurring [Member] | Discounted Cash Flows Approach Valuation Technique [Member] | Minimum [Member] | Farmer Mac Guaranteed Securities - Rural Utilities [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value Inputs, discount rate	1.00%	0.80%
Level 3 [Member] | Farmer Mac Guarantee [Member] | Fair Value, Measurements, Recurring [Member] | Discounted Cash Flows Approach Valuation Technique [Member] | Maximum [Member] | Farm & Ranch Guaranteed Securities [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value Inputs, discount rate	3.60%	3.40%
Level 3 [Member] | Farmer Mac Guarantee [Member] | Fair Value, Measurements, Recurring [Member] | Discounted Cash Flows Approach Valuation Technique [Member] | Maximum [Member] | USDA Guarantees - Farmer Mac Guaranteed Securities [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value Inputs, discount rate	3.30%	3.40%
Fair Value Inputs, Constant Prepayment Rate	14.00%	17.00%
Level 3 [Member] | Farmer Mac Guarantee [Member] | Fair Value, Measurements, Recurring [Member] | Discounted Cash Flows Approach Valuation Technique [Member] | Maximum [Member] | Farmer Mac Guaranteed Securities - Rural Utilities [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value Inputs, discount rate	3.30%	2.90%
Level 3 [Member] | Farmer Mac Guarantee [Member] | Fair Value, Measurements, Recurring [Member] | Discounted Cash Flows Approach Valuation Technique [Member] | Weighted Average [Member] | Farm & Ranch Guaranteed Securities [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value Inputs, discount rate	1.70%	1.60%
Level 3 [Member] | Farmer Mac Guarantee [Member] | Fair Value, Measurements, Recurring [Member] | Discounted Cash Flows Approach Valuation Technique [Member] | Weighted Average [Member] | USDA Guarantees - Farmer Mac Guaranteed Securities [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value Inputs, discount rate	2.00%	2.10%
Fair Value Inputs, Constant Prepayment Rate	13.00%	14.00%
Level 3 [Member] | Farmer Mac Guarantee [Member] | Fair Value, Measurements, Recurring [Member] | Discounted Cash Flows Approach Valuation Technique [Member] | Weighted Average [Member] | Farmer Mac Guaranteed Securities - Rural Utilities [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value Inputs, discount rate	1.80%	1.60%
Level 3 [Member] | USDA Guarantee [Member] | Fair Value, Measurements, Recurring [Member] | USDA Guaranteed Securities [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Available-for-sale securities	1,566,691	1,486,595
Trading securities	62,319	104,188
Marketable Securities	$ 1,629,010	$ 1,590,783
Level 3 [Member] | USDA Guarantee [Member] | Fair Value, Measurements, Recurring [Member] | Discounted Cash Flows Approach Valuation Technique [Member] | Minimum [Member] | USDA Guaranteed Securities [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value Inputs, discount rate	1.20%	1.40%
Fair Value Inputs, Constant Prepayment Rate	0.00%	0.00%
Level 3 [Member] | USDA Guarantee [Member] | Fair Value, Measurements, Recurring [Member] | Discounted Cash Flows Approach Valuation Technique [Member] | Maximum [Member] | USDA Guaranteed Securities [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value Inputs, discount rate	5.30%	5.30%
Fair Value Inputs, Constant Prepayment Rate	24.00%	26.00%
Level 3 [Member] | USDA Guarantee [Member] | Fair Value, Measurements, Recurring [Member] | Discounted Cash Flows Approach Valuation Technique [Member] | Weighted Average [Member] | USDA Guaranteed Securities [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value Inputs, discount rate	3.30%	3.40%
Fair Value Inputs, Constant Prepayment Rate	6.00%	10.00%