v3.25.4
Cover - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2025
Mar. 05, 2026
Jun. 30, 2025
Cover [Abstract]      
Document Type 10-K    
Document Annual Report true    
Document Period End Date Dec. 31, 2025    
Current Fiscal Year End Date --12-31    
Document Transition Report false    
Entity File Number 001-42175    
Entity Registrant Name FIRSTSUN CAPITAL BANCORP    
Entity Incorporation, State or Country Code DE    
Entity Tax Identification Number 81-4552413    
Entity Address, Address Line One 1400 16th Street    
Entity Address, Address Line Two Suite 250    
Entity Address, City or Town Denver    
Entity Address, State or Province CO    
Entity Address, Postal Zip Code 80202    
City Area Code 303    
Local Phone Number 831-6704    
Title of 12(b) Security Common Stock, $0.0001 Par Value    
Trading Symbol FSUN    
Security Exchange Name NASDAQ    
Entity Well-known Seasoned Issuer No    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Interactive Data Current Yes    
Entity Filer Category Accelerated Filer    
Entity Small Business false    
Entity Emerging Growth Company true    
Entity Ex Transition Period false    
ICFR Auditor Attestation Flag false    
Document Financial Statement Error Correction Flag false    
Entity Shell Company false    
Entity Public Float     $ 395.2
Entity Common Stock, Shares Outstanding   27,923,333  
Documents Incorporated by Reference
DOCUMENTS INCORPORATED BY REFERENCE
Portions of the Proxy Statement (the “2026 Proxy Statement”) for the 2026 Annual Meeting of Shareholders to be held on June 5, 2026, are incorporated by reference into Part III of this Annual Report on Form 10-K.
   
Entity Central Index Key 0001709442    
Document Fiscal Year Focus 2025    
Document Fiscal Period Focus FY    
Amendment Flag false