REVENUE RECOGNITION - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2018
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Amortization of Deferred Charges	$ 20,400	$ 25,200
Deferred Revenue	18,000	25,500		$ 25,800
Deferred Revenue, Revenue Recognized	25,400	25,100
Total Groupon, Inc. Stockholders' Equity
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Cumulative effect of change in accounting principle, net of tax		(88,945)	$ 3,234
Prepaid Expenses and Other Current Assets
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Deferred Costs	2,501	2,923
Other Noncurrent Assets
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Deferred Costs	$ 10,133	$ 11,285