| Document and Entity Information Document and Entity Information | Mar. 03, 2020 |
| Cover page. | |
| Document Type | 8-K |
| Document Period End Date | Mar. 3, 2020 |
| Entity Registrant Name | ALIGN TECHNOLOGY INC |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 0-32259 |
| Entity Tax Identification Number | 94-3267295 |
| Entity Address, Address Line One | 2820 Orchard Parkway |
| Entity Address, City or Town | San Jose |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 95134 |
| City Area Code | 408 |
| Local Phone Number | 470-1000 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common stock, $0.0001 par value |
| Trading Symbol | ALGN |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0001097149 |
| Amendment Flag | false |
