Intangible Assets - Goodwill (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2020 USD ($)
Goodwill
Goodwill gross, beginning balance	$ 949,936
Accumulated impairment loss, beginning balance	(197,344)
Goodwill net, beginning balance	752,592
Foreign currency translation adjustments	(13,413)
Goodwill gross, ending balance	936,523
Accumulated impairment loss, ending balance	(197,344)
Goodwill net, ending balance	739,179
North America
Goodwill
Goodwill gross, beginning balance	561,513
Accumulated impairment loss, beginning balance	(7,303)
Goodwill net, beginning balance	554,210
Foreign currency translation adjustments	(2,778)
Goodwill gross, ending balance	558,735
Accumulated impairment loss, ending balance	(7,303)
Goodwill net, ending balance	551,432
Europe & Africa
Goodwill
Goodwill gross, beginning balance	236,992
Accumulated impairment loss, beginning balance	(50,003)
Goodwill net, beginning balance	186,989
Foreign currency translation adjustments	(10,842)
Goodwill gross, ending balance	226,150
Accumulated impairment loss, ending balance	(50,003)
Goodwill net, ending balance	176,147
Australia & New Zealand
Goodwill
Goodwill gross, beginning balance	151,431
Accumulated impairment loss, beginning balance	(140,038)
Goodwill net, beginning balance	11,393
Foreign currency translation adjustments	207
Goodwill gross, ending balance	151,638
Accumulated impairment loss, ending balance	(140,038)
Goodwill net, ending balance	$ 11,600