SUPPLEMENTAL CONSOLIDATED BALANCE SHEETS AND STATEMENTS OF OPERATIONS INFORMATION - Schedule of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification for impact of U.S. tax rate change			$ 161
Other comprehensive income (loss)	$ 22	$ (5,259)	324	$ (12,442)
Accumulated other comprehensive income (loss)	32,329		32,329		$ 31,844
Foreign currency translation adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Foreign currency translation adjustments, beginning balance			30,962
Reclassification for impact of U.S. tax rate change			0
Other comprehensive income (loss)			1,166
Foreign currency translation adjustments, ending balance	32,128		32,128
Unrealized gain (loss) on available-for-sale securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss)			(842)
Unrealized gain (loss) on available-for-sale securities, beginning balance			882
Unrealized gain (loss) on available-for-sale securities, ending balance	201		201
Total Groupon, Inc. Stockholders' Equity
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss)			324
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss)	$ 32,329		$ 32,329		$ 31,844