DOCUMENT AND ENTITY INFORMATION - shares	3 Months Ended
	Mar. 31, 2019	Apr. 25, 2019
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	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Mar. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Amendment Flag	false
Trading Symbol	AGM
Entity Small Business	false
Entity Emerging Growth Company	false
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		9,167,448