Restructuring Charges - Changes to Restructuring Liability by Major Restructuring Activity (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Restructuring Cost And Reserve [Line Items]
Beginning balance				$ 3,435
Restructuring charges		$ 1,387	$ 2,186	3,467	$ 5,799
Cash payments				(1,641)
Non-cash items	[1]			(1,167)
Adjustment to liability				(8)
Ending balance		4,086		4,086
GES | Severance & Employee Benefits
Restructuring Cost And Reserve [Line Items]
Beginning balance				1,976
Restructuring charges				463
Cash payments				(869)
Non-cash items	[1]			0
Adjustment to liability				(3)
Ending balance		1,567		1,567
GES | Facilities
Restructuring Cost And Reserve [Line Items]
Beginning balance				1,433
Restructuring charges				2,974
Cash payments				(689)
Non-cash items	[1]			(1,167)
Adjustment to liability				(44)
Ending balance		2,507		2,507
Other Restructuring | Severance & Employee Benefits
Restructuring Cost And Reserve [Line Items]
Beginning balance				26
Restructuring charges				30
Cash payments				(83)
Adjustment to liability				39
Ending balance		$ 12		$ 12

[1] Represents non-cash adjustments related to a write-down of certain ROU assets and leasehold improvements as a result of vacating certain facilities prior to the lease term.