Financial Instruments - Cash, Cash Equivalents and Marketable Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Amortized Cost
Cash, cash equivalents and marketable securities	$ 903,061	$ 981,569
Gross Unrealized Gains
Cash, cash equivalents and marketable securities	3	7
Gross Unrealized Losses
Cash, cash equivalents and marketable securities	(539)	(812)
Fair Value
Cash and cash equivalents	865,805	937,438
Marketable securities	36,720	43,326
Cash, cash equivalents and marketable securities	902,525	980,764
Cash
Amortized Cost
Cash and cash equivalents	816,224	887,682
Fair Value
Cash and cash equivalents	816,224	887,682
Cash and Cash Equivalents
Fair Value
Cash, cash equivalents and marketable securities	865,805	937,438
Cash and Cash Equivalents \| Cash
Fair Value
Cash and cash equivalents	816,224	887,682
Marketable securities, short-term
Fair Value
Cash, cash equivalents and marketable securities	33,101	35,304
Marketable securities, long-term
Fair Value
Cash, cash equivalents and marketable securities	3,619	8,022
Money market funds
Amortized Cost
Cash and cash equivalents	49,581	49,756
Fair Value
Cash and cash equivalents	49,581	49,756
Money market funds \| Cash and Cash Equivalents
Fair Value
Cash and cash equivalents	49,581	49,756
Corporate bonds
Amortized Cost
Marketable securities	26,535	31,943
Gross Unrealized Gains
Marketable securities	3	5
Gross Unrealized Losses
Marketable securities	(417)	(676)
Fair Value
Marketable securities	26,121	31,272
Corporate bonds \| Cash and Cash Equivalents
Fair Value
Marketable securities		0
Corporate bonds \| Marketable securities, short-term
Fair Value
Marketable securities	24,551	28,704
Corporate bonds \| Marketable securities, long-term
Fair Value
Marketable securities	1,570	2,568
U.S. government treasury bonds
Amortized Cost
Marketable securities	4,871	4,855
Gross Unrealized Gains
Marketable securities	0	0
Gross Unrealized Losses
Marketable securities	(101)	(99)
Fair Value
Marketable securities	4,770	4,756
U.S. government treasury bonds \| Marketable securities, short-term
Fair Value
Marketable securities	2,721	0
U.S. government treasury bonds \| Marketable securities, long-term
Fair Value
Marketable securities	2,049	4,756
Asset-backed securities
Amortized Cost
Marketable securities	586	1,416
Gross Unrealized Gains
Marketable securities	0	2
Gross Unrealized Losses
Marketable securities	(1)	(1)
Fair Value
Marketable securities	585	1,417
Asset-backed securities \| Marketable securities, short-term
Fair Value
Marketable securities	585	719
Asset-backed securities \| Marketable securities, long-term
Fair Value
Marketable securities	0	698
Municipal bonds
Amortized Cost
Marketable securities		702
Gross Unrealized Gains
Marketable securities		0
Gross Unrealized Losses
Marketable securities		(2)
Fair Value
Marketable securities		700
Municipal bonds \| Cash and Cash Equivalents
Fair Value
Marketable securities		0
Municipal bonds \| Marketable securities, short-term
Fair Value
Marketable securities		700
Municipal bonds \| Marketable securities, long-term
Fair Value
Marketable securities		0
U.S. government agency bonds
Amortized Cost
Marketable securities	5,264	5,215
Gross Unrealized Gains
Marketable securities	0	0
Gross Unrealized Losses
Marketable securities	(20)	(34)
Fair Value
Marketable securities	5,244	5,181
U.S. government agency bonds \| Marketable securities, short-term
Fair Value
Marketable securities	5,244	5,181
U.S. government agency bonds \| Marketable securities, long-term
Fair Value
Marketable securities	$ 0	$ 0

Cash And Cash Equivalents, Amortized Cost

No definition available.

Name:	algn_CashAndCashEquivalentsAmortizedCost
Namespace Prefix:	algn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Cash And Cash Equivalents, And Debt Securities Available For Sale

+ References

No definition available.

+ Details

Name:	algn_CashAndCashEquivalentsAndDebtSecuritiesAvailableForSale
Namespace Prefix:	algn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Cash And Cash Equivalents And Debt Securities Available For Sale, Amortized Cost

+ References

No definition available.

+ Details

Name:	algn_CashAndCashEquivalentsAndDebtSecuritiesAvailableForSaleAmortizedCost
Namespace Prefix:	algn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Cash And Cash Equivalents And Debt Securities Available For Sale, Gross Unrealized Gain

+ References

No definition available.

+ Details

Name:	algn_CashAndCashEquivalentsAndDebtSecuritiesAvailableForSaleGrossUnrealizedGain
Namespace Prefix:	algn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Cash And Cash Equivalents And Debt Securities Available For Sale, Gross Unrealized Loss

+ References

No definition available.

+ Details

Name:	algn_CashAndCashEquivalentsAndDebtSecuritiesAvailableForSaleGrossUnrealizedLoss
Namespace Prefix:	algn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Financial Instruments, Amortized Cost

+ References

No definition available.

+ Details

Name:	algn_FinancialInstrumentsAmortizedCostAbstract
Namespace Prefix:	algn_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Financial Instruments, Fair Value

+ References

No definition available.

+ Details

Name:	algn_FinancialInstrumentsFairValueAbstract
Namespace Prefix:	algn_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Financial Instruments, Gross Unrealized Gain

+ References

No definition available.

+ Details

Name:	algn_FinancialInstrumentsGrossUnrealizedGainAbstract
Namespace Prefix:	algn_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Financial Instruments, Gross Unrealized Loss

+ References

No definition available.

+ Details

Name:	algn_FinancialInstrumentsGrossUnrealizedLossAbstract
Namespace Prefix:	algn_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

+ Details

Name:	us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

+ Details

Name:	us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(1))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479440/944-210-S99-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479130/326-30-45-1

+ Details

Name:	us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (aa)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481830/320-10-45-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(6))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479853/942-210-S99-1

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479130/326-30-45-1

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesDebtSecurities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(1))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483467/210-10-45-1

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482740/230-10-45-4

+ Details

Name:	us-gaap_CashAndCashEquivalentsAtCarryingValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_CashAndCashEquivalentsAxis=us-gaap_CashMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BalanceSheetLocationAxis=us-gaap_CashAndCashEquivalentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BalanceSheetLocationAxis=algn_MarketableSecuritiesShortTermMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BalanceSheetLocationAxis=algn_MarketableSecuritiesLongTermMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_MoneyMarketFundsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_CorporateBondSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_USTreasuryBondSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_AssetBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_MunicipalBondsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_USGovernmentCorporationsAndAgenciesSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: