Basis of Presentation and Summary of Significant Accounting Polices - Restructuring Expenses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Restructuring Cost and Reserve
Restructuring expenses	$ 9,443	$ 8,928	$ 6,586
Corporate
Restructuring Cost and Reserve
Restructuring expenses	338	3,874	1,343
Europe & Africa | Operating Segments
Restructuring Cost and Reserve
Restructuring expenses	7,325	3,828	1,646
North America | Operating Segments
Restructuring Cost and Reserve
Restructuring expenses	1,665	1,226	3,597
Australia & New Zealand | Operating Segments
Restructuring Cost and Reserve
Restructuring expenses	115	0	0
Facilities closures
Restructuring Cost and Reserve
Restructuring expenses	7,030	2,562	634
Severance and benefits
Restructuring Cost and Reserve
Restructuring expenses	2,204	2,899	5,952
Professional fees and other costs
Restructuring Cost and Reserve
Restructuring expenses	$ 209	$ 3,467	$ 0