DOCUMENT AND ENTITY INFORMATION DOCUMENT AND ENTITY INFORMATION - shares	6 Months Ended
	Jun. 30, 2018	Aug. 01, 2018
Entity Information [Line Items]
Entity Registrant Name	FEDERAL AGRICULTURAL MORTGAGE CORP
Entity Central Index Key	0000845877
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Document Type	10-Q
Document Period End Date	Jun. 30, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q2
Amendment Flag	false
Trading Symbol	AGM
Common Class A, Voting [Member]
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		1,030,780
Common Class B, Voting [Member]
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		500,301
Common Class C, Non-Voting [Member]
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		9,137,500