Intangible Assets - Goodwill and Net Carrying Amounts (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($)
Goodwill
Goodwill gross, beginning balance	$ 939,185
Accumulated impairment loss, beginning balance	(190,041)
Goodwill net, beginning balance	749,144
Foreign currency translation adjustments	10,751
Goodwill gross, ending balance	949,936
Accumulated impairment loss, ending balance	(197,344)
Goodwill net, ending balance	752,592
North America
Goodwill
Goodwill gross, beginning balance	556,570
Accumulated impairment loss, beginning balance	0
Goodwill net, beginning balance	556,570
Foreign currency translation adjustments	4,943
Goodwill gross, ending balance	561,513
Accumulated impairment loss, ending balance	(7,303)
Goodwill net, ending balance	554,210
Europe & Africa
Goodwill
Goodwill gross, beginning balance	231,121
Accumulated impairment loss, beginning balance	(50,003)
Goodwill net, beginning balance	181,118
Foreign currency translation adjustments	5,871
Goodwill gross, ending balance	236,992
Accumulated impairment loss, ending balance	(50,003)
Goodwill net, ending balance	186,989
Australia & New Zealand
Goodwill
Goodwill gross, beginning balance	151,494
Accumulated impairment loss, beginning balance	(140,038)
Goodwill net, beginning balance	11,456
Foreign currency translation adjustments	(63)
Goodwill gross, ending balance	151,431
Accumulated impairment loss, ending balance	(140,038)
Goodwill net, ending balance	$ 11,393