Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2021	Nov. 01, 2021
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Trading Symbol	MDRX
Entity Registrant Name	ALLSCRIPTS HEALTHCARE SOLUTIONS, INC.
Entity Central Index Key	0001124804
Entity Current Reporting Status	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Shell Company	false
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		122,572,462
Entity File Number	001-35547
Entity Tax Identification Number	36-4392754
Entity Address, Address Line One	222 Merchandise Mart
Entity Address, Address Line Two	Suite 2024
Entity Address, City or Town	Chicago
Entity Address, State or Province	IL
Entity Address, Postal Zip Code	60654
City Area Code	800
Local Phone Number	334-8534
Entity Interactive Data Current	Yes
Title of 12(b) Security	Common Stock, par value $0.01 per share
Security Exchange Name	NASDAQ
Entity Incorporation, State or Country Code	DE
Document Quarterly Report	true
Document Transition Report	false