Farmer Mac Guaranteed Securities and USDA Guaranteed Securities - Trading Securities (Details) - USDA Securities [Member] - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Debt and Equity Securities, FV-NI [Line Items]
Trading, at fair value	$ 9,999	$ 13,515
USDA Guarantees [Member]
Debt and Equity Securities, FV-NI [Line Items]
Debt Securities, Trading, Amortized Cost	10,292	13,888
Trading, at fair value	$ 9,999	$ 13,515
Trading Securities, Weighted-Average Yield	5.21%	5.33%

Amount of investment in debt security measured at fair value with change in fair value recognized in net income (trading) and investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.4)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Name:	us-gaap_TradingSecurities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant