Cover Page - shares	9 Months Ended
	Sep. 30, 2020	Nov. 02, 2020
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2020
Document Transition Report	false
Entity File Number	1-35335
Entity Registrant Name	Groupon, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	27-0903295
Entity Address, Address Line One	600 W Chicago Avenue
Entity Address, Address Line Two	Suite 400
Entity Address, City or Town	Chicago
Entity Address, State or Province	IL
Entity Address, Postal Zip Code	60654
City Area Code	(312)
Local Phone Number	334-1579
Title of 12(b) Security	Common stock, par value $0.0001 per share
Trading Symbol	GRPN
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Smaller Reporting Company	false
Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		28,812,655
Entity Central Index Key	0001490281
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3