Guarantees and Long Term Standby Purchase Commitments - Off-Balance Sheet Guaranteed Securities (Details) - Variable Interest Entity, Not Primary Beneficiary [Member] - USD ($) $ in Thousands		Dec. 31, 2016	Dec. 31, 2015
Guarantor Obligations [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted		$ 1,802,631	$ 1,809,194
Farm & Ranch [Member]
Guarantor Obligations [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted		415,441	514,051
USDA Guarantees [Member]
Guarantor Obligations [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted		103,976	10,272
Institutional Credit [Member]
Guarantor Obligations [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted		983,214	984,871
Revolving Credit Facility [Member] | Institutional Credit [Member]
Guarantor Obligations [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted	[1]	$ 300,000	$ 300,000

[1] Relates to a revolving floating rate AgVantage facility subject to specified contractual terms. Farmer Mac receives a fixed fee based on the full dollar amount of the facility.