Dividends, Term Without Prior Regulatory Approval, Preceding Period of Net Income

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Share-based Compensation Arrangement By Share-based Payment Award, Fair Value Assumptions, Expected Volatility, Number Of Comparable Companies

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Stock Repurchase Program, Shares Held-In-Treasury Per Share

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Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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Face amount or stated value per share of common stock.

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The maximum number of common shares permitted to be issued by an entity's charter and bylaws.

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Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

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Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation.

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Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Amount of cost to be recognized for option under share-based payment arrangement.

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Cash outflow in the form of capital distributions and dividends to common shareholders, preferred shareholders and noncontrolling interests.

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Face amount or stated value per share of preferred stock nonredeemable or redeemable solely at the option of the issuer.

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The maximum number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) permitted to be issued by an entity's charter and bylaws.

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Total number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) issued to shareholders (includes related preferred shares that were issued, repurchased, and remain in the treasury). May be all or portion of the number of preferred shares authorized. Excludes preferred shares that are classified as debt.

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Aggregate share number for all nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer) held by stockholders. Does not include preferred shares that have been repurchased.

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Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Number of shares authorized for issuance under share-based payment arrangement.

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Gross number of share options (or share units) granted during the period.

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Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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Percentage of vesting of award under share-based payment arrangement.

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Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Number of shares used to settle grantee's tax withholding obligation for award under share-based payment arrangement.

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Total number of shares issued during the period, including shares forfeited, as a result of Restricted Stock Awards.

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Stockholders' Equity - Narrative (Details)		12 Months Ended
Stockholders' Equity - Narrative (Details)	Dec. 30, 2021 USD ($) shares	Dec. 31, 2021 USD ($) company $ / shares shares	Dec. 31, 2020 USD ($) $ / shares shares	Dec. 31, 2019 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Preferred stock, shares authorized (in shares)		10,000,000	10,000,000
Preferred stock, par value (in dollars per share) \| $ / shares		$ 0.0001	$ 0.0001
Preferred stock, shares issued (in shares)		0	0
Preferred stock, shares outstanding (in shares)		0	0
Common stock, shares authorized (in shares)		50,000,000	50,000,000
Common stock, par value (in dollars per share) \| $ / shares		$ 0.0001	$ 0.0001
Common stock, shares issued (in shares)		19,903,342	19,878,713
Common Stock, shares outstanding (in shares)		18,346,288	18,321,659
Stock repurchase program, shares Held-in-treasury per share (in dollars per share) \| $ / shares		$ 24.50
Dividends, term without prior regulatory approval, preceding period of net income		2 years
Payments of dividends \| $		$ 0	$ 0	$ 32,000,000
Granted (in shares)		26,336	133,707
Share-based payment arrangement, compensation cost \| $		$ 2,998,000	$ 2,335,000	$ 2,147,000
Total unrecognized compensation cost related to non-vested stock options granted \| $		1,160,000
Intrinsic value of the stock options \| $		$ 18,042,000	$ 10,660,000
Option awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award contractual term		10 years
Total unrecognized compensation cost related to non-vested stock options granted, period		3 years 5 months 1 day
Option awards \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility, number of Comparable companies \| company		25
Option awards \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility, number of Comparable companies \| company		30
First Anniversaries \| Option awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage		25.00%
Second Anniversaries \| Option awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage		25.00%
Third Anniversaries \| Option awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage		25.00%
Fourth Anniversaries \| Option awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage		25.00%
FirstSun Capital Bancorp 2017 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate shares of common stock (in shares)		1,977,292
FirstSun Capital Bancorp 2017 Equity Incentive Plan \| Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of common stock on restricted stock grants (in shares)	24,099
Shares withheld for tax withholding obligations (in shares)	13,822
Grant date fair value of awards \| $	$ 1,250,000
FirstSun Capital Bancorp 2017 Equity Incentive Plan \| Restricted Stock, Vest In Conjunction With Annual Stockholders Meeting
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of common stock on restricted stock grants (in shares)	530
Grant date fair value of awards \| $	$ 18,000
FirstSun Capital Bancorp 2021 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate shares of common stock (in shares)		2,476,571
Granted (in shares)		0