Cover
| Cover | Apr. 01, 2022 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Aug. 11, 2022 |
| Entity Registrant Name | FIRSTSUN CAPITAL BANCORP |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 333-258176 |
| 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 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | true |
| Entity Ex Transition Period | false |
| Entity Central Index Key | 0001709442 |
| Amendment Flag | false |