Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2018	Nov. 05, 2018	Dec. 31, 2017
Document and Entity Information [Abstract]
Preferred Stock, Shares Outstanding			0
Entity Registrant Name	Groupon, Inc.
Entity Central Index Key	0001490281
Entity Filer Category	Large Accelerated Filer
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Type	10-Q
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q3
Entity Common Stock, Shares Outstanding		570,780,015
Smaller Reporting Company	false
Emerging Growth Company	false