CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Condensed Statement of Income Captions [Line Items]
Income (loss) from continuing operations	$ 47,175	$ 3,802	$ (47,874)	$ (22,470)
Other comprehensive income (loss) from continuing operations:
Net change in unrealized gain (loss) on foreign currency translation adjustments			1,166
Net change in unrealized gain (loss) on defined benefit pension plan	0	0	0	585
Net unrealized gain (loss) during the period	94	(225)	(948)	(938)
Reclassification adjustment for realized (gain) loss on investment included in income (loss) from continuing operations	0	0	106	(1,341)
Net change in unrealized gain (loss) on available-for-sale securities (net of tax effect of $46 and $0 for the three months ended September 30, 2018 and 2017, respectively, and $60 and $0 for the nine months ended September 30, 2018 and 2017, respectively)	94	(225)	(842)	(2,279)
Income (loss) from discontinued operations	0	(862)	0	(1,751)
Other comprehensive income (loss) from discontinued operations - Foreign currency translation adjustments:
Other comprehensive income (loss)	22	(5,259)	324	(12,442)
Comprehensive income (loss)	47,197	(2,319)	(47,550)	(53,174)
Comprehensive income (loss) attributable to noncontrolling interests	(2,560)	(2,881)	(9,433)	(9,460)
Comprehensive income (loss) attributable to Groupon, Inc.	44,637	(5,200)	(56,983)	(62,634)
Tax effect	46	0	60	0
Continuing Operations
Other comprehensive income (loss) from continuing operations:
Net change in unrealized gain (loss) on foreign currency translation adjustments	(72)	(5,034)	1,166	(10,748)
Other comprehensive income (loss) from discontinued operations - Foreign currency translation adjustments:
Comprehensive income (loss)	47,197	(1,457)	(47,550)	(34,912)
Discontinued Operations, Disposed of by Sale
Other comprehensive income (loss) from continuing operations:
Net change in unrealized gain (loss) on foreign currency translation adjustments	0	0	0	(16,511)
Other comprehensive income (loss) from discontinued operations - Foreign currency translation adjustments:
Net unrealized gain (loss) during the period	0	0	0	(1,793)
Reclassification adjustment included in net income (loss) from discontinued operations	0	0	0	(14,718)
Other comprehensive income (loss)	$ 0	$ (862)	$ 0	$ (18,262)