Accounting Policies - Consolidation of Variable Interest Entities (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2016 USD ($) subsidiary		Dec. 31, 2015 USD ($)
Variable Interest Entity [Line Items]
Number of Subsidiaries | subsidiary	3
Loans held for investment in consolidated trusts, at amortized cost	$ 922,666		$ 708,111
Debt securities of consolidated trusts held by third parties	928,050		713,536
Farm & Ranch [Member]
Variable Interest Entity [Line Items]
Other Liabilities	5,400		5,400
USDA Guarantees [Member]
Variable Interest Entity [Line Items]
Unamortized Premium/(Discount)	600		(200)
Institutional Credit [Member]
Variable Interest Entity [Line Items]
Fair Value Adjustment	1,000		1,400
On-balance sheet [Member]
Variable Interest Entity [Line Items]
Loans held for investment in consolidated trusts, at amortized cost	922,666		708,111
Debt securities of consolidated trusts held by third parties	928,050	[1]	713,536	[2]
On-balance sheet [Member] | Farm & Ranch [Member]
Variable Interest Entity [Line Items]
Loans held for investment in consolidated trusts, at amortized cost	922,666		708,111
Debt securities of consolidated trusts held by third parties	928,050	[1]	713,536	[2]
On-balance sheet [Member] | USDA Guarantees [Member]
Variable Interest Entity [Line Items]
Loans held for investment in consolidated trusts, at amortized cost	0		0
Debt securities of consolidated trusts held by third parties	0	[1]	0	[2]
On-balance sheet [Member] | Rural Utilities [Member]
Variable Interest Entity [Line Items]
Loans held for investment in consolidated trusts, at amortized cost	0		0
Debt securities of consolidated trusts held by third parties	0	[1]	0	[2]
On-balance sheet [Member] | Institutional Credit [Member]
Variable Interest Entity [Line Items]
Loans held for investment in consolidated trusts, at amortized cost	0		0
Debt securities of consolidated trusts held by third parties	0	[1]	0	[2]
On-balance sheet [Member] | Corporate Segment [Member]
Variable Interest Entity [Line Items]
Loans held for investment in consolidated trusts, at amortized cost	0		0
Debt securities of consolidated trusts held by third parties	0	[1]	0	[2]
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	1,467,441	[3],[4]	1,494,323	[5],[6]
Off-balance sheet [Member] | Farm & Ranch [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	466,479	[3],[4]	514,051	[5],[6]
Off-balance sheet [Member] | USDA Guarantees [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	30,962	[3],[4]	10,272	[5],[6]
Off-balance sheet [Member] | Rural Utilities [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	0	[3],[4]	0	[5],[6]
Off-balance sheet [Member] | Institutional Credit [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	[3],[4]	970,000	[5],[6]
Off-balance sheet [Member] | Corporate Segment [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	0	[3],[4]	0	[5],[6]
Farmer Mac Guaranteed Securities: | 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	64,409	[7]	62,760	[8]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	62,886	[3]	61,553	[5]
Farmer Mac Guaranteed Securities: | On-balance sheet [Member] | Farm & Ranch [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	0	[7]	0	[8]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	0	[3]	0	[5]
Farmer Mac Guaranteed Securities: | On-balance sheet [Member] | USDA Guarantees [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	33,447	[7]	31,360	[8]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	32,886	[3]	31,553	[5]
Farmer Mac Guaranteed Securities: | On-balance sheet [Member] | Rural Utilities [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	0	[7]	0	[8]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	0	[3]	0	[5]
Farmer Mac Guaranteed Securities: | On-balance sheet [Member] | Institutional Credit [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	30,962	[7]	31,400	[8]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	30,000	[3]	30,000	[5]
Farmer Mac Guaranteed Securities: | On-balance sheet [Member] | Corporate Segment [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	0	[7]	0	[8]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	0	[3]	0	[5]
Investment Securities [Member]
Variable Interest Entity [Line Items]
Unamortized Premium/(Discount)	5,271		5,936
Investment Securities [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	812,501	[9]	917,292	[10]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	813,063	[3],[9]	918,121	[5],[10]
Investment Securities [Member] | On-balance sheet [Member] | Farm & Ranch [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	0	[9]	0	[10]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	0	[3],[9]	0	[5],[10]
Investment Securities [Member] | On-balance sheet [Member] | USDA Guarantees [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	0	[9]	0	[10]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	0	[3],[9]	0	[5],[10]
Investment Securities [Member] | On-balance sheet [Member] | Rural Utilities [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	0	[9]	0	[10]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	0	[3],[9]	0	[5],[10]
Investment Securities [Member] | On-balance sheet [Member] | Institutional Credit [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	0	[9]	0	[10]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	0	[3],[9]	0	[5],[10]
Investment Securities [Member] | On-balance sheet [Member] | Corporate Segment [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	812,501	[9]	917,292	[10]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	$ 813,063	[3],[9]	$ 918,121	[5],[10]

[1] Includes borrower remittances of $5.4 million. The borrower remittances have not been passed through to third party investors as of June 30, 2016.

[2] Includes borrower remittances of $5.4 million, which have not been passed through to third party investors as of December 31, 2015.

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

[4] 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.

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

[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.

[7] Includes $0.6 million of unamortized premiums and discounts and fair value adjustments related to the USDA Guarantees line of business. Includes fair value adjustments related to the Institutional Credit line of business of $1.0 million.

[8] Includes $0.2 million of unamortized premiums and discounts and fair value adjustments related to the USDA Guarantees line of business. Includes fair value adjustments related to the Institutional Credit line of business of $1.4 million.

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

[10] Includes auction-rate certificates, asset-backed securities, and GSE-guaranteed mortgage-backed securities.