Quarterly report pursuant to Section 13 or 15(d)

Cover Page

Cover Page - shares
6 Months Ended
Jun. 30, 2022
Aug. 01, 2022
Document Information [Line Items]    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Jun. 30, 2022  
Document Transition Report false  
Entity File Number 001-39644  
Entity Registrant Name Archaea Energy Inc.  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 85-2867266  
Entity Address, Address Line One 4444 Westheimer Road  
Entity Address, Address Line Two Suite G450  
Entity Address, City or Town Houston  
Entity Address, State or Province TX  
Entity Address, Postal Zip Code 77027  
City Area Code 346  
Local Phone Number 708-8272  
Title of 12(b) Security Class A Common Stock, par value $0.0001 per share  
Trading Symbol LFG  
Security Exchange Name NYSE  
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 false  
Amendment Flag false  
Document Fiscal Period Focus Q2  
Document Fiscal Year Focus 2022  
Current Fiscal Year End Date --12-31  
Entity Central Index Key 0001823766  
Class A Units    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   80,717,757
Class B Units    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   39,060,418