Accounting Policies - Principles of Consolidation (Details) (USD $)	3 Months Ended			6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013	Jun. 30, 2014		Jun. 30, 2013	Dec. 31, 2013
Variable Interest Entity [Line Items]
Number of Subsidiaries	2
Loans held for investment in consolidated trust, at amortized cost (1)	$ 668,736,000			$ 668,736,000			$ 629,989,000
Debt securities of consolidated trusts held by third parties (2)	377,518,000			377,518,000			261,760,000
Guarantee and commitment fees	6,403,000		6,759,000	12,921,000		13,371,000
Fair Value of Securities Received as Collateral that Have Been Resold or Repledged	1,640,686,000			1,640,686,000			0
Federal Funds Sold and Securities Purchased under Agreements to Resell Pledged as Collateral	1,600,000,000			1,600,000,000			0
Fair Value of Securities Received as Collateral that Have Been Resold or Repledged	1,600,000,000			1,600,000,000			0
On-balance sheet [Member]
Variable Interest Entity [Line Items]
Loans held for investment in consolidated trust, at amortized cost (1)	668,736,000	[1]		668,736,000	[1]		629,989,000	[2]
Debt securities of consolidated trusts held by third parties (2)	377,518,000	[3]		377,518,000	[3]		261,760,000	[4]
Farm & Ranch [Member]
Variable Interest Entity [Line Items]
Other Liabilities	5,600,000			5,600,000			2,300,000
Guarantee and commitment fees	3,807,000		3,703,000	7,716,000		7,374,000
Farm & Ranch [Member] | On-balance sheet [Member]
Variable Interest Entity [Line Items]
Loans held for investment in consolidated trust, at amortized cost (1)	371,960,000	[1]		371,960,000	[1]		259,509,000	[2]
Debt securities of consolidated trusts held by third parties (2)	377,518,000	[3]		377,518,000	[3]		261,760,000	[4]
USDA Guarantees [Member]
Variable Interest Entity [Line Items]
Debt Instrument, Unamortized Discount (Premium), Net	400,000			400,000			100,000
Guarantee and commitment fees	23,000		42,000	49,000		75,000
USDA Guarantees [Member] | On-balance sheet [Member]
Variable Interest Entity [Line Items]
Loans held for investment in consolidated trust, at amortized cost (1)	0	[1]		0	[1]		0	[2]
Debt securities of consolidated trusts held by third parties (2)	0	[3]		0	[3]		0	[4]
Rural Utilities [Member]
Variable Interest Entity [Line Items]
Debt Instrument, Unamortized Premium	4,200,000			4,200,000			16,200,000
Guarantee and commitment fees	0		0	0		948,000
Rural Utilities [Member] | On-balance sheet [Member]
Variable Interest Entity [Line Items]
Loans held for investment in consolidated trust, at amortized cost (1)	296,776,000	[1]		296,776,000	[1]		370,480,000
Debt securities of consolidated trusts held by third parties (2)	0	[3]		0	[3]		0
Institutional Credit [Member] [Member]
Variable Interest Entity [Line Items]
Debt Instrument, Unamortized Discount (Premium), Net	2,900,000			2,900,000			3,200,000
Guarantee and commitment fees	3,086,000		3,209,000	6,200,000		5,349,000
Institutional Credit [Member] [Member] | On-balance sheet [Member]
Variable Interest Entity [Line Items]
Loans held for investment in consolidated trust, at amortized cost (1)	0	[1]		0	[1]		0	[2]
Debt securities of consolidated trusts held by third parties (2)	0	[3]		0	[3]		0	[4]
Corporate [Member]
Variable Interest Entity [Line Items]
Guarantee and commitment fees	0		0	0		0
Corporate [Member] | On-balance sheet [Member]
Variable Interest Entity [Line Items]
Loans held for investment in consolidated trust, at amortized cost (1)	0	[1]		0	[1]		0	[2]
Debt securities of consolidated trusts held by third parties (2)	0	[3]		0	[3]		0	[4]
FMMSC [Member]
Variable Interest Entity [Line Items]
Guarantee and commitment fees	2,600,000		2,700,000	5,200,000		5,400,000
Farmer Mac Guaranteed Securities Trusts [Member] | On-balance sheet [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	53,930,000	[5]		53,930,000	[5]		54,482,000	[6]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	50,675,000	[7]		50,675,000	[7]		51,088,000	[8]
Farmer Mac Guaranteed Securities Trusts [Member] | Farm & Ranch [Member] | On-balance sheet [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	0	[5]		0	[5]		0	[6]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	0	[7]		0	[7]		0	[8]
Farmer Mac Guaranteed Securities Trusts [Member] | Farm & Ranch [Member] | Off-balance sheet [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	704,376,000			704,376,000			765,751,000
Farmer Mac Guaranteed Securities Trusts [Member] | USDA Guarantees [Member] | On-balance sheet [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	21,044,000	[5]		21,044,000	[5]		21,234,000	[6]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	20,675,000	[7]		20,675,000	[7]		21,088,000	[8]
Farmer Mac Guaranteed Securities Trusts [Member] | USDA Guarantees [Member] | Off-balance sheet [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	16,662,000	[7],[9]		16,662,000	[7],[9]		20,222,000	[8],[9]
Farmer Mac Guaranteed Securities Trusts [Member] | Rural Utilities [Member] | On-balance sheet [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	0			0			0	[6]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	0			0			0	[8]
Farmer Mac Guaranteed Securities Trusts [Member] | Rural Utilities [Member] | Off-balance sheet [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	0	[7],[9]		0	[7],[9]		0
Farmer Mac Guaranteed Securities Trusts [Member] | Institutional Credit [Member] [Member] | On-balance sheet [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	32,886,000	[5]		32,886,000	[5]		33,248,000	[6]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	30,000,000	[7]		30,000,000	[7]		30,000,000	[8]
Farmer Mac Guaranteed Securities Trusts [Member] | Institutional Credit [Member] [Member] | Off-balance sheet [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	970,000,000	[7],[9]		970,000,000	[7],[9]		970,000,000	[8],[9]
Farmer Mac Guaranteed Securities Trusts [Member] | Corporate [Member] | On-balance sheet [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	0			0			0	[6]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	0	[7]		0	[7]		0	[8]
Investment Securities Trusts [Member] | On-balance sheet [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	488,783,000	[10]		488,783,000	[10]		533,688,000	[8]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	492,849,000	[10],[7]		492,849,000	[10],[7]		540,726,000	[11],[8]
Investment Securities Trusts [Member] | Off-balance sheet [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	1,691,038,000	[7],[9]		1,691,038,000	[7],[9]		1,755,973,000	[8],[9]
Investment Securities Trusts [Member] | Farm & Ranch [Member] | On-balance sheet [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	0	[10]		0	[10]		0	[8]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	0	[10],[7]		0	[10],[7]		0	[11],[8]
Investment Securities Trusts [Member] | USDA Guarantees [Member] | On-balance sheet [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	0	[10]		0	[10]		0	[8]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	0	[10],[7]		0	[10],[7]		0	[11],[8]
Investment Securities Trusts [Member] | Rural Utilities [Member] | On-balance sheet [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	0			0			0	[8]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	0	[10],[7]		0	[10],[7]		0	[11],[8]
Investment Securities Trusts [Member] | Institutional Credit [Member] [Member] | On-balance sheet [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	0	[10]		0	[10]		0	[8]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	0	[10],[7]		0	[10],[7]		0	[11],[8]
Investment Securities Trusts [Member] | Corporate [Member] | On-balance sheet [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	488,783,000			488,783,000			533,688,000
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	492,849,000			492,849,000			540,726,000	[11],[8]
Investment Securities Trusts [Member] | Corporate [Member] | Off-balance sheet [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	$ 0	[7],[9]		$ 0	[7],[9]		$ 0	[8],[9]

[1] (1) Includes unamortized premiums related to the Rural Utilities line of business of $4.2 million.

[2] (1) Includes unamortized premiums related to the Rural Utilities line of business of $16.2 million.

[3] (2) Includes unamortized premiums and borrower remittances of $5.6 million. The borrower remittances have not been passed through to third party investors as of June 30, 2014.

[4] (2) Includes borrower remittances of $2.3 million, which have not been passed through to third party investors as of December 31, 2013.

[5] (3) Includes unamortized premiums and discounts and fair value adjustments related to the USDA Guarantees and Institutional Credit lines of business of $0.4 million and $2.9 million, respectively.

[6] (3) Includes unamortized premiums and discounts and fair value adjustments related to the USDA Guarantees and Institutional Credit lines of business of $0.1 million and $3.2 million, respectively.

[7] (4) Farmer Mac uses unpaid principal balance and outstanding face amount of investment securities to represent maximum exposure to loss.

[8] (4) Farmer Mac uses unpaid principal balance and the outstanding face amount of investment securities to represent maximum exposure to loss.

[9] (6) The amount under the Farm & Ranch line of business relates to unconsolidated trusts where Farmer Mac determined it was not the primary beneficiary due to shared power with an unrelated party.

[10] (5) Includes auction-rate certificates, asset-backed securities, and government-sponsored enterprise ("GSE")-guaranteed mortgage-backed securities.

[11] (5) Includes auction-rate certificates, asset-backed securities, and GSE-guaranteed mortgage-backed securities.