COVER PAGE - shares	6 Months Ended
	Jun. 30, 2019	Jul. 25, 2019
Entity Information [Line Items]
Document Quarterly Report	true
Document Transition Report	false
Document Type	10-Q
Document Period End Date	Jun. 30, 2019
Entity File Number	001-14951
Entity Registrant Name	FEDERAL AGRICULTURAL MORTGAGE CORPORATION
Entity Incorporation, State or Country Code	X1
Entity Tax Identification Number	52-1578738
Entity Address, Address Line One	1999 K Street, N.W., 4th Floor,
Entity Address, City or Town	Washington,
Entity Address, Postal Zip Code	20006
Entity Address, State or Province	DC
City Area Code	(202)
Local Phone Number	872-7700
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Central Index Key	0000845877
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q2
Amendment Flag	false
Common Class A, Voting [Member]
Entity Information [Line Items]
Title of 12(b) Security	Class A voting common stock
Trading Symbol	AGM.A
Security Exchange Name	NYSE
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]
Title of 12(b) Security	Class C non-voting common stock
Trading Symbol	AGM
Security Exchange Name	NYSE
Entity Common Stock, Shares Outstanding		9,169,154
Series A Preferred Stock [Member]
Entity Information [Line Items]
Title of 12(b) Security	5.875% Non-Cumulative Preferred Stock, Series A
Trading Symbol	AGM.PRA
Security Exchange Name	NYSE
Series C Preferred Stock [Member]
Entity Information [Line Items]
Title of 12(b) Security	6.000% Fixed-to-Floating Rate Non-Cumulative Preferred Stock, Series C
Trading Symbol	AGM.PRC
Security Exchange Name	NYSE
Series D Preferred Stock [Member]
Entity Information [Line Items]
Title of 12(b) Security	5.700% Non-Cumulative Preferred Stock, Series D
Trading Symbol	AGM.PRD
Security Exchange Name	NYSE