Segments and Geographical Information - Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information [Line Items]
Net revenues	$ 734,144	$ 607,341	$ 1,637,421	$ 1,757,009
Gross profit	534,088	437,554	1,152,772	1,271,939
Income from operations	177,069	127,152	173,987	391,343
Depreciation and amortization	24,486	19,706	68,769	57,194
Impairments and other (gains) charges	0	(6,792)	0	22,990
Litigation settlement gain	0	0	0	(51,000)
Interest income	329	3,478	2,788	9,576
Other income (expense), net	7,147	(2,211)	(12,368)	5,935
Net income before provision for income taxes and equity in losses of investee	184,545	128,419	164,407	406,854
Operating Segments
Segment Reporting Information [Line Items]
Income from operations	296,686	244,712	519,272	714,908
Clear Aligner
Segment Reporting Information [Line Items]
Net revenues	620,764	516,265	1,400,716	1,482,172
Gross profit	463,747	379,202	1,007,605	1,096,702
Income from operations	261,774	211,952	467,078	614,622
Depreciation and amortization	10,413	9,306	30,231	27,851
Impairments and other (gains) charges	0	(6,792)	0	22,990
Litigation settlement gain	0	0	0	(51,000)
Systems and Services
Segment Reporting Information [Line Items]
Net revenues	113,380	91,076	236,705	274,837
Gross profit	70,341	58,352	145,167	175,237
Income from operations	34,912	32,760	52,194	100,286
Depreciation and amortization	5,092	1,987	11,882	5,349
Unallocated corporate expenses
Segment Reporting Information [Line Items]
Income from operations	(119,617)	(117,560)	(345,285)	(323,565)
Depreciation and amortization	$ 8,981	$ 8,413	$ 26,656	$ 23,994