Restructuring Charges - Changes to Restructuring Liability by Major Restructuring Activity (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Restructuring Cost And Reserve [Line Items]
Beginning balance				$ 3,435
Restructuring charges		$ 1,426	$ 787	2,080	$ 3,613
Cash payments				(1,118)
Non-cash items	[1]			(1,167)
Adjustment to liability				(27)
Ending balance		3,257		3,257
GES | Severance & Employee Benefits
Restructuring Cost And Reserve [Line Items]
Beginning balance				1,976
Restructuring charges				377
Cash payments				(316)
Non-cash items	[1]			(355)
Adjustment to liability				(2)
Ending balance		1,680		1,680
GES | Facilities
Restructuring Cost And Reserve [Line Items]
Beginning balance				1,433
Restructuring charges				1,673
Cash payments				(719)
Non-cash items	[1]			812
Adjustment to liability				(10)
Ending balance		1,565		1,565
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 during the first quarter of 2022 prior to the lease term.