Overview and Basis of Presentation - Revenue in Condensed Consolidated Statement of Operations (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenue:
Total revenue	$ 358,163	$ 339,099	$ 999,268	$ 1,029,680
Calculated under Revenue Guidance in Effect before Topic 606
Revenue:
Total revenue		339,099		1,029,680
Exhibition and Event Services [Member] | Calculated under Revenue Guidance in Effect before Topic 606
Revenue:
Total revenue		198,868		750,111
Exhibits and Environments [Member] | Calculated under Revenue Guidance in Effect before Topic 606
Revenue:
Total revenue		33,251		119,988
Pursuit Services [Member] | Calculated under Revenue Guidance in Effect before Topic 606
Revenue:
Total revenue		$ 106,980		$ 159,581