Guarantees - Significant Cash Flows Received From and Paid to Trusts (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Proceeds from sale of Farmer Mac Guaranteed Securities	$ 165,054	$ 321,414	$ 382,929
Guarantee fees received	$ 1,365	$ 1,413	$ 1,920

Cash received for fees during the current period. This element excludes cash proceeds from license fees.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 25
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3536-108585

Name:	us-gaap_ProceedsFromFeesReceived
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration