Common Stock Repurchase Programs - Additional Information (Details) - USD ($) $ in Thousands, shares in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Mar. 31, 2020	May 31, 2018
ALGNMay2018 Repurchase [Member]
Share Repurchases [Line Items]
Stock Repurchase Program, Remaining Authorized Repurchase Amount			$ 100,000
May 2018 Repurchase Program
Share Repurchases [Line Items]
Accelerated share repurchase (shares)	0.8	0.1
Share repurchase price (in dollars per share)	$ 264.93	$ 356.54
Repurchased	$ 200,000	$ 50,000
Value of repurchased common stock				$ 600,000
2018 ASR
Share Repurchases [Line Items]
Accelerated share repurchase (shares)		0.2
Share repurchase price (in dollars per share)		$ 213.18
Repurchased		$ 50,000
2019 ASR
Share Repurchases [Line Items]
Accelerated share repurchase (shares)	1.1
Share repurchase price (in dollars per share)	$ 176.61
Repurchased	$ 200,000