Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2022	Nov. 04, 2022
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2022
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q3
Entity Registrant Name	ALTA EQUIPMENT GROUP INC.
Entity Central Index Key	0001759824
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Shell Company	false
Entity Small Business	false
Entity Emerging Growth Company	false
Entity File Number	001-38864
Entity Incorporation State Country Code	DE
Entity Tax Identification Number	83-2583782
Entity Address Address Line1	13211 Merriman Road
Entity Address City or Town	Livonia
Entity Address State or Province	MI
Entity Address Postal Zip Code	48150
City Area Code	248
Local Phone Number	449-6700
Document Quarterly Report	true
Document Transition Report	false
Entity Common Stock Shares Outstanding		32,194,243
Common Stock
Document Information [Line Items]
Title of 12(b) Security	Common stock, $0.0001 par value per share
Trading Symbol	ALTG
Security Exchange Name	NYSE
Preferred Stock
Document Information [Line Items]
Title of 12(b) Security	Depositary Shares
Trading Symbol	ALTG PRA
Security Exchange Name	NYSE