Goodwill and Other Intangible Assets - Summary of Goodwill Balances by Component and Segment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Goodwill [Line Items]
Balance, beginning	$ 287,983	$ 261,330
Business acquisitions		20,684
Goodwill impairment	(185,789)
Foreign currency translation adjustments	(415)	5,969
Other	(1,932)
Balance, ending	99,847	287,983
GES North America
Goodwill [Line Items]
Balance, beginning	155,276	154,944
Goodwill impairment	(154,989)
Foreign currency translation adjustments	(287)	332
Balance, ending		155,276
GES EMEA
Goodwill [Line Items]
Balance, beginning	30,829	29,954
Goodwill impairment	(29,042)
Foreign currency translation adjustments	(1,787)	875
Balance, ending		30,829
Pursuit
Goodwill [Line Items]
Balance, beginning	101,878	76,432
Business acquisitions		20,684
Goodwill impairment	(1,758)
Foreign currency translation adjustments	1,659	4,762
Other	(1,932)
Balance, ending	$ 99,847	$ 101,878