Quarterly report pursuant to Section 13 or 15(d)


Cover - shares
9 Months Ended
Sep. 30, 2021
Nov. 10, 2021
Document Information [Line Items]    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Sep. 30, 2021  
Document Transition Report false  
Entity File Number 001-39994  
Entity Incorporation, State or Country Code E9  
Entity Tax Identification Number 98-1571400  
Entity Address, Address Line One 40 West 57th Street  
Entity Address, Address Line Two 33rd Floor  
Entity Address, City or Town New York  
Entity Address, State or Province NY  
Entity Address, Postal Zip Code 10019  
City Area Code 212  
Local Phone Number 287-6767  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Non-accelerated Filer  
Entity Small Business true  
Entity Emerging Growth Company true  
Entity Ex Transition Period false  
Entity Shell Company true  
Entity Central Index Key 0001836176  
Current Fiscal Year End Date --12-31  
Document Fiscal Year Focus 2021  
Document Fiscal Period Focus Q3  
Amendment Flag false  
Units Each Consisting Of One Share Of Class Common Stock And One Fourth Of One Redeemable Warrant    
Document Information [Line Items]    
Title of 12(b) Security Units, each consisting of oneClass A ordinary share, $0.0001 par value, and one-fourth of one redeemable warrant  
Trading Symbol ATMR.U  
Security Exchange Name NYSE  
Class A common stock    
Document Information [Line Items]    
Title of 12(b) Security Class A ordinary shares, $0.0001 par value  
Trading Symbol ATMR  
Security Exchange Name NYSE  
Common shares outstanding (in shares)   34,500,000
Redeemable warrants, each whole warrant exercisable    
Document Information [Line Items]    
Title of 12(b) Security Warrants, each whole warrant exercisable for one Class A ordinary share, each at an exercise price of $11.50 per share  
Trading Symbol ATMR WS  
Security Exchange Name NYSE  
Class B common stock    
Document Information [Line Items]    
Common shares outstanding (in shares)   8,625,000