Goodwill and Other Intangible Assets - Summary of Goodwill Balances by Component and Segment (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($)
Goodwill [Line Items]
Balance, beginning	$ 270,551
Foreign currency translation adjustments	(757)
Balance, ending	269,794
GES U.S.
Goodwill [Line Items]
Balance, beginning	148,277
Balance, ending	148,277
GES International
Goodwill [Line Items]
Balance, beginning	38,840
Foreign currency translation adjustments	931
Balance, ending	39,771
Pursuit
Goodwill [Line Items]
Balance, beginning	83,434
Foreign currency translation adjustments	(1,688)
Balance, ending	$ 81,746