Intangible Assets - Goodwill (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2021 USD ($)
Goodwill
Goodwill gross, beginning balance	$ 956,446
Accumulated impairment loss, beginning balance	(197,344)
Goodwill net, beginning balance	759,102
Foreign currency translation adjustments	1,709
Goodwill gross, ending balance	958,155
Accumulated impairment loss, ending balance	(197,344)
Goodwill net, ending balance	760,811
North America
Goodwill
Goodwill gross, beginning balance	563,734
Accumulated impairment loss, beginning balance	(7,303)
Goodwill net, beginning balance	556,431
Foreign currency translation adjustments	1,252
Goodwill gross, ending balance	564,986
Accumulated impairment loss, ending balance	(7,303)
Goodwill net, ending balance	557,683
Europe & Africa
Goodwill
Goodwill gross, beginning balance	240,151
Accumulated impairment loss, beginning balance	(50,003)
Goodwill net, beginning balance	190,148
Foreign currency translation adjustments	621
Goodwill gross, ending balance	240,772
Accumulated impairment loss, ending balance	(50,003)
Goodwill net, ending balance	190,769
Australia & New Zealand
Goodwill
Goodwill gross, beginning balance	152,561
Accumulated impairment loss, beginning balance	(140,038)
Goodwill net, beginning balance	12,523
Foreign currency translation adjustments	(164)
Goodwill gross, ending balance	152,397
Accumulated impairment loss, ending balance	(140,038)
Goodwill net, ending balance	$ 12,359