v3.23.1

INITIAL PUBLIC OFFERING (Details)	Mar. 08, 2021 $ / shares shares
Initial Public Offering
Subsidiary, Sale of Stock [Line Items]
Number of units issued (in shares)	15,525,000
Share price (in dollars per share) \| $ / shares	$ 10.00
Number of shares in a unit	1
Shares issuable per warrant (in shares)	1
Number of warrants issued per unit (in shares)	0.25
Over-allotment
Subsidiary, Sale of Stock [Line Items]
Number of units issued (in shares)	2,025,000
Exercise price of warrants (in dollars per share) \| $ / shares	$ 11.50

Represents the number of shares in a unit.

+ References

No definition available.

+ Details

Name:	ataq_NumberOfSharesIssuedPerUnit
Namespace Prefix:	ataq_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the number of warrants in a unit.

+ References

No definition available.

+ Details

Name:	ataq_NumberOfWarrantsIssuedPerUnit
Namespace Prefix:	ataq_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of new units issued during the period.

+ References

No definition available.

+ Details

Name:	ataq_UnitsIssuedDuringPeriodSharesNewIssues
Namespace Prefix:	ataq_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Exercise price per share or per unit of warrants or rights outstanding.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI https://asc.fasb.org/extlink&oid=126973232&loc=d3e21475-112644

+ Details

Name:	us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of securities into which each warrant or right may be converted. For example, but not limited to, each warrant may be converted into two shares.

+ References

No definition available.

+ Details

Name:	us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByEachWarrantOrRight
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Price of a single share of a number of saleable stocks of a company.

+ References

No definition available.

+ Details

Name:	us-gaap_SharePrice
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_SubsidiarySaleOfStockLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_SubsidiarySaleOfStockAxis=us-gaap_IPOMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsidiarySaleOfStockAxis=us-gaap_OverAllotmentOptionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Altimar Acquisition Corp. III 10-Q