Segment Information - Reconciliation of Assets from Reportable Segments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of assets from segment
Total Assets	$ 1,318,691	$ 922,541	$ 919,899
Total Depreciation and Amortization	58,964	56,842	55,114
Capital expenditures	76,147	83,345	56,621
GES | North America
Reconciliation of assets from segment
Total Assets	475,279	406,484	406,038
Total Depreciation and Amortization	29,321	30,855	30,260
Capital expenditures	19,099	19,263	18,900
GES | EMEA
Reconciliation of assets from segment
Total Assets	132,975	111,798	110,788
Total Depreciation and Amortization	6,260	7,071	7,004
Capital expenditures	7,098	7,065	6,521
Pursuit
Reconciliation of assets from segment
Total Assets	589,205	357,630	350,256
Total Depreciation and Amortization	23,154	18,690	17,653
Capital expenditures	49,934	56,865	30,786
Corporate and other
Reconciliation of assets from segment
Total Assets	121,232	46,629	52,817
Total Depreciation and Amortization	229	226	197
Capital expenditures	$ 16	$ 152	$ 414