Charges Related To Restructuring Activities - (Details) - USD ($)	3 Months Ended							12 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Restructuring Reserve [Roll Forward]
Beginning Balance			$ 6,253,000				$ 7,027,000	$ 6,253,000	$ 7,027,000	$ 1,682,000
Charges	$ (377,000)	$ (547,000)	(1,552,000)	$ (2,701,000)	$ (1,580,000)	$ (1,685,000)	(1,392,000)	(2,534,000)	(7,358,000)	(11,829,000)
Payments								(8,305,000)	(8,132,000)	(6,484,000)
Ending Balance				6,253,000				482,000	6,253,000	7,027,000
Severance
Restructuring Reserve [Roll Forward]
Beginning Balance			6,249,000				7,023,000	6,249,000	7,023,000	1,657,000
Charges								(1,860,000)	(7,012,000)	(11,562,000)
Payments								(7,627,000)	(7,786,000)	(6,196,000)
Ending Balance				6,249,000				482,000	6,249,000	7,023,000
Contract Terminations
Restructuring Reserve [Roll Forward]
Beginning Balance			4,000				4,000	4,000	4,000	25,000
Charges								(674,000)	(346,000)	(267,000)
Payments								(678,000)	(346,000)	(288,000)
Ending Balance				4,000				0	4,000	4,000
North America
Restructuring Reserve [Roll Forward]
Beginning Balance			179,000				211,000	179,000	211,000	681,000
Charges								(964,000)	(1,306,000)	(1,617,000)
Payments								(661,000)	(1,338,000)	(2,087,000)
Ending Balance				179,000				482,000	179,000	211,000
North America | Severance
Restructuring Reserve [Roll Forward]
Beginning Balance			179,000				211,000	179,000	211,000	656,000
Charges								(964,000)	(1,306,000)	(1,573,000)
Payments								(661,000)	(1,338,000)	(2,018,000)
Ending Balance				179,000				482,000	179,000	211,000
North America | Contract Terminations
Restructuring Reserve [Roll Forward]
Beginning Balance			0				0	0	0	25,000
Charges								0	0	(44,000)
Payments								0	0	(69,000)
Ending Balance				0				0	0	0
Europe
Restructuring Reserve [Roll Forward]
Beginning Balance			5,908,000				6,410,000	5,908,000	6,410,000	181,000
Charges								(1,560,000)	(5,934,000)	(9,579,000)
Payments								(7,468,000)	(6,436,000)	(3,350,000)
Ending Balance				5,908,000				0	5,908,000	6,410,000
Europe | Severance
Restructuring Reserve [Roll Forward]
Beginning Balance			5,904,000				6,406,000	5,904,000	6,406,000	181,000
Charges								(886,000)	(5,588,000)	(9,356,000)
Payments								(6,790,000)	(6,090,000)	(3,131,000)
Ending Balance				5,904,000				0	5,904,000	6,406,000
Europe | Contract Terminations
Restructuring Reserve [Roll Forward]
Beginning Balance			4,000				4,000	4,000	4,000	0
Charges								(674,000)	(346,000)	(223,000)
Payments								(678,000)	(346,000)	(219,000)
Ending Balance				4,000				0	4,000	4,000
All Other
Restructuring Reserve [Roll Forward]
Beginning Balance			166,000				406,000	166,000	406,000	820,000
Charges								(10,000)	(118,000)	(633,000)
Payments								(176,000)	(358,000)	(1,047,000)
Ending Balance				166,000				0	166,000	406,000
All Other | Severance
Restructuring Reserve [Roll Forward]
Beginning Balance			166,000				406,000	166,000	406,000	820,000
Charges								(10,000)	(118,000)	(633,000)
Payments								(176,000)	(358,000)	(1,047,000)
Ending Balance				166,000				0	166,000	406,000
All Other | Contract Terminations
Restructuring Reserve [Roll Forward]
Beginning Balance			$ 0				$ 0	0	0	0
Charges								0	0	0
Payments								0	0	0
Ending Balance				$ 0				$ 0	$ 0	$ 0