v3.19.3
Document and Entity Information - shares
9 Months Ended
Sep. 30, 2019
Nov. 06, 2019
Document Information [Line Items]    
Entity Registrant Name Falcon Minerals Corp  
Entity Central Index Key 0001703785  
Amendment Flag false  
Current Fiscal Year End Date --12-31  
Document Type 10-Q  
Document Period End Date Sep. 30, 2019  
Document Fiscal Year Focus 2019  
Document Fiscal Period Focus Q3  
Entity Filer Category Accelerated Filer  
Entity Current Reporting Status Yes  
Entity Small Business false  
Entity Emerging Growth Company true  
Entity Ex Transition Period false  
Entity File Number 001-38158  
Entity Tax Identification Number 82-0820780  
Entity Address, Address Line One 510 Madison Avenue  
Entity Address, Address Line Two 8th Floor  
Entity Address, City or Town New York  
Entity Address, State or Province NY  
Entity Address, Postal Zip Code 10022  
City Area Code 212  
Local Phone Number 506-5925  
Entity Shell Company false  
Entity Interactive Data Current Yes  
Entity Incorporation, State or Country Code DE  
Document Quarterly Report true  
Document Transition Report false  
Class A common stock [Member]    
Document Information [Line Items]    
Title of 12(b) Security Class A Common Stock, par value $0.0001 per share  
Trading Symbol FLMN  
Security Exchange Name NASDAQ  
Entity Common Stock Shares Outstanding   45,950,716
Warrants [Member]    
Document Information [Line Items]    
Title of 12(b) Security Warrants, each to purchase one share of Class A Common Stock  
Trading Symbol FLMNW  
Security Exchange Name NASDAQ  
Class C common stock [Member]    
Document Information [Line Items]    
Entity Common Stock Shares Outstanding   40,000,000