3.26.1 html 672 426 1 false 122 0 false 11 false false R1.htm 0000001 - Document - Cover Sheet http://www.coastalbank.com/role/Cover Cover Cover 1 false false R2.htm 9952151 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) Sheet http://www.coastalbank.com/role/CONDENSEDCONSOLIDATEDBALANCESHEETSUNAUDITED CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) Statements 2 false false R3.htm 9952152 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) (Parenthetical) Sheet http://www.coastalbank.com/role/CONDENSEDCONSOLIDATEDBALANCESHEETSUNAUDITEDParenthetical CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) (Parenthetical) Statements 3 false false R4.htm 9952153 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED) Sheet http://www.coastalbank.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFINCOMEUNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED) Statements 4 false false R5.htm 9952154 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) Sheet http://www.coastalbank.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFCOMPREHENSIVEINCOMEUNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) Statements 5 false false R6.htm 9952155 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (UNAUDITED) Sheet http://www.coastalbank.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFCHANGESINSHAREHOLDERSEQUITYUNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (UNAUDITED) Statements 6 false false R7.htm 9952156 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) Sheet http://www.coastalbank.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFCASHFLOWSUNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) Statements 7 false false R8.htm 9952157 - Disclosure - Description of Business and Summary of Significant Accounting Policies Sheet http://www.coastalbank.com/role/DescriptionofBusinessandSummaryofSignificantAccountingPolicies Description of Business and Summary of Significant Accounting Policies Notes 8 false false R9.htm 9952158 - Disclosure - Recent accounting standards Sheet http://www.coastalbank.com/role/Recentaccountingstandards Recent accounting standards Notes 9 false false R10.htm 9952159 - Disclosure - Investment Securities Sheet http://www.coastalbank.com/role/InvestmentSecurities Investment Securities Notes 10 false false R11.htm 9952160 - Disclosure - Loans and Allowance for Credit Losses Sheet http://www.coastalbank.com/role/LoansandAllowanceforCreditLosses Loans and Allowance for Credit Losses Notes 11 false false R12.htm 9952161 - Disclosure - Deposits Sheet http://www.coastalbank.com/role/Deposits Deposits Notes 12 false false R13.htm 9952162 - Disclosure - Leases Sheet http://www.coastalbank.com/role/Leases Leases Notes 13 false false R14.htm 9952163 - Disclosure - Stock-Based Compensation Sheet http://www.coastalbank.com/role/StockBasedCompensation Stock-Based Compensation Notes 14 false false R15.htm 9952164 - Disclosure - Fair Value Measurements Sheet http://www.coastalbank.com/role/FairValueMeasurements Fair Value Measurements Notes 15 false false R16.htm 9952165 - Disclosure - Earnings Per Common Share Sheet http://www.coastalbank.com/role/EarningsPerCommonShare Earnings Per Common Share Notes 16 false false R17.htm 9952166 - Disclosure - Segment Reporting Sheet http://www.coastalbank.com/role/SegmentReporting Segment Reporting Notes 17 false false R18.htm 995445 - Disclosure - Insider Trading Arrangements Sheet http://xbrl.sec.gov/ecd/role/InsiderTradingArrangements Insider Trading Arrangements Notes 18 false false R19.htm 9955511 - Disclosure - Description of Business and Summary of Significant Accounting Policies (Policies) Sheet http://www.coastalbank.com/role/DescriptionofBusinessandSummaryofSignificantAccountingPoliciesPolicies Description of Business and Summary of Significant Accounting Policies (Policies) Policies http://www.coastalbank.com/role/DescriptionofBusinessandSummaryofSignificantAccountingPolicies 19 false false R20.htm 9955512 - Disclosure - Investment Securities (Tables) Sheet http://www.coastalbank.com/role/InvestmentSecuritiesTables Investment Securities (Tables) Tables http://www.coastalbank.com/role/InvestmentSecurities 20 false false R21.htm 9955513 - Disclosure - Loans and Allowance for Credit Losses (Tables) Sheet http://www.coastalbank.com/role/LoansandAllowanceforCreditLossesTables Loans and Allowance for Credit Losses (Tables) Tables http://www.coastalbank.com/role/LoansandAllowanceforCreditLosses 21 false false R22.htm 9955514 - Disclosure - Deposits (Tables) Sheet http://www.coastalbank.com/role/DepositsTables Deposits (Tables) Tables http://www.coastalbank.com/role/Deposits 22 false false R23.htm 9955515 - Disclosure - Leases (Tables) Sheet http://www.coastalbank.com/role/LeasesTables Leases (Tables) Tables http://www.coastalbank.com/role/Leases 23 false false R24.htm 9955516 - Disclosure - Stock-Based Compensation (Tables) Sheet http://www.coastalbank.com/role/StockBasedCompensationTables Stock-Based Compensation (Tables) Tables http://www.coastalbank.com/role/StockBasedCompensation 24 false false R25.htm 9955517 - Disclosure - Fair Value Measurements (Tables) Sheet http://www.coastalbank.com/role/FairValueMeasurementsTables Fair Value Measurements (Tables) Tables http://www.coastalbank.com/role/FairValueMeasurements 25 false false R26.htm 9955518 - Disclosure - Earnings Per Common Share (Tables) Sheet http://www.coastalbank.com/role/EarningsPerCommonShareTables Earnings Per Common Share (Tables) Tables http://www.coastalbank.com/role/EarningsPerCommonShare 26 false false R27.htm 9955519 - Disclosure - Segment Reporting (Tables) Sheet http://www.coastalbank.com/role/SegmentReportingTables Segment Reporting (Tables) Tables http://www.coastalbank.com/role/SegmentReporting 27 false false R28.htm 9955520 - Disclosure - Description of Business and Summary of Significant Accounting Policies - Additional Information (Details) Sheet http://www.coastalbank.com/role/DescriptionofBusinessandSummaryofSignificantAccountingPoliciesAdditionalInformationDetails Description of Business and Summary of Significant Accounting Policies - Additional Information (Details) Details 28 false false R29.htm 9955521 - Disclosure - Investments Securities - Amortized Cost and Fair Values of Investments in Debt Securities (Details) Sheet http://www.coastalbank.com/role/InvestmentsSecuritiesAmortizedCostandFairValuesofInvestmentsinDebtSecuritiesDetails Investments Securities - Amortized Cost and Fair Values of Investments in Debt Securities (Details) Details 29 false false R30.htm 9955522 - Disclosure - Investments Securities - Amortized Cost and Fair Value of Debt Securities by Contractual Maturity (Details) Sheet http://www.coastalbank.com/role/InvestmentsSecuritiesAmortizedCostandFairValueofDebtSecuritiesbyContractualMaturityDetails Investments Securities - Amortized Cost and Fair Value of Debt Securities by Contractual Maturity (Details) Details 30 false false R31.htm 9955523 - Disclosure - Investments Securities - Additional Information (Details) Sheet http://www.coastalbank.com/role/InvestmentsSecuritiesAdditionalInformationDetails Investments Securities - Additional Information (Details) Details 31 false false R32.htm 9955524 - Disclosure - Investments Securities - Summary of Investment Securities Continuous Unrealized Loss Position (Details) Sheet http://www.coastalbank.com/role/InvestmentsSecuritiesSummaryofInvestmentSecuritiesContinuousUnrealizedLossPositionDetails Investments Securities - Summary of Investment Securities Continuous Unrealized Loss Position (Details) Details 32 false false R33.htm 9955525 - Disclosure - Loans and Allowance for Credit Losses - Additional Information (Details) Sheet http://www.coastalbank.com/role/LoansandAllowanceforCreditLossesAdditionalInformationDetails Loans and Allowance for Credit Losses - Additional Information (Details) Details 33 false false R34.htm 9955526 - Disclosure - Loans and Allowance for Credit Losses - Composition of Loan Portfolio (Details) Sheet http://www.coastalbank.com/role/LoansandAllowanceforCreditLossesCompositionofLoanPortfolioDetails Loans and Allowance for Credit Losses - Composition of Loan Portfolio (Details) Details 34 false false R35.htm 9955527 - Disclosure - Loans and Allowance for Credit Losses - Breakdown of Consumer Loan Portfolio by Segment and Type of Loan (Details) Sheet http://www.coastalbank.com/role/LoansandAllowanceforCreditLossesBreakdownofConsumerLoanPortfoliobySegmentandTypeofLoanDetails Loans and Allowance for Credit Losses - Breakdown of Consumer Loan Portfolio by Segment and Type of Loan (Details) Details 35 false false R36.htm 9955528 - Disclosure - Loans and Allowance for Credit Losses - Summary of an Age Analysis of Past Due Loans (Details) Sheet http://www.coastalbank.com/role/LoansandAllowanceforCreditLossesSummaryofanAgeAnalysisofPastDueLoansDetails Loans and Allowance for Credit Losses - Summary of an Age Analysis of Past Due Loans (Details) Details 36 false false R37.htm 9955529 - Disclosure - Loans and Allowance for Credit Losses - Analysis of Nonaccrual Loans by Category (Details) Sheet http://www.coastalbank.com/role/LoansandAllowanceforCreditLossesAnalysisofNonaccrualLoansbyCategoryDetails Loans and Allowance for Credit Losses - Analysis of Nonaccrual Loans by Category (Details) Details 37 false false R38.htm 9955530 - Disclosure - Loans and Allowance for Credit Losses - Loans Experiencing Financial Difficulty and Modified (Details) Sheet http://www.coastalbank.com/role/LoansandAllowanceforCreditLossesLoansExperiencingFinancialDifficultyandModifiedDetails Loans and Allowance for Credit Losses - Loans Experiencing Financial Difficulty and Modified (Details) Details 38 false false R39.htm 9955531 - Disclosure - Loans and Allowance for Credit Losses - Summary of Risk Category of Loans by Class of Loans (Details) Sheet http://www.coastalbank.com/role/LoansandAllowanceforCreditLossesSummaryofRiskCategoryofLoansbyClassofLoansDetails Loans and Allowance for Credit Losses - Summary of Risk Category of Loans by Class of Loans (Details) Details 39 false false R40.htm 9955532 - Disclosure - Loans and Allowance for Credit Losses - Summary of Amortized Cost of CCBX Loans (Details) Sheet http://www.coastalbank.com/role/LoansandAllowanceforCreditLossesSummaryofAmortizedCostofCCBXLoansDetails Loans and Allowance for Credit Losses - Summary of Amortized Cost of CCBX Loans (Details) Details 40 false false R41.htm 9955533 - Disclosure - Loans and Allowance for Credit Losses - Summary of Loans by Credit Quality Risk Rating (Details) Sheet http://www.coastalbank.com/role/LoansandAllowanceforCreditLossesSummaryofLoansbyCreditQualityRiskRatingDetails Loans and Allowance for Credit Losses - Summary of Loans by Credit Quality Risk Rating (Details) Details 41 false false R42.htm 9955534 - Disclosure - Loans and Allowance for Credit Losses - Summary of Allocation of Allowance for Loan Loss as well as Activity in Allowance for Loan Loss Attributed to Various Segments in Loan (Details) Sheet http://www.coastalbank.com/role/LoansandAllowanceforCreditLossesSummaryofAllocationofAllowanceforLoanLossaswellasActivityinAllowanceforLoanLossAttributedtoVariousSegmentsinLoanDetails Loans and Allowance for Credit Losses - Summary of Allocation of Allowance for Loan Loss as well as Activity in Allowance for Loan Loss Attributed to Various Segments in Loan (Details) Details 42 false false R43.htm 9955535 - Disclosure - Loans and Allowance for Credit Losses - Summary of Collateral Dependent Loans (Details) Sheet http://www.coastalbank.com/role/LoansandAllowanceforCreditLossesSummaryofCollateralDependentLoansDetails Loans and Allowance for Credit Losses - Summary of Collateral Dependent Loans (Details) Details 43 false false R44.htm 9955536 - Disclosure - Deposits - Composition of Consolidated Deposits (Details) Sheet http://www.coastalbank.com/role/DepositsCompositionofConsolidatedDepositsDetails Deposits - Composition of Consolidated Deposits (Details) Details 44 false false R45.htm 9955537 - Disclosure - Deposits - Schedule of Maturity Distribution of Time Deposits (Details) Sheet http://www.coastalbank.com/role/DepositsScheduleofMaturityDistributionofTimeDepositsDetails Deposits - Schedule of Maturity Distribution of Time Deposits (Details) Details 45 false false R46.htm 9955538 - Disclosure - Deposits - Additional Information (Details) Sheet http://www.coastalbank.com/role/DepositsAdditionalInformationDetails Deposits - Additional Information (Details) Details 46 false false R47.htm 9955539 - Disclosure - Leases - Additional Information (Details) Sheet http://www.coastalbank.com/role/LeasesAdditionalInformationDetails Leases - Additional Information (Details) Details 47 false false R48.htm 9955540 - Disclosure - Leases - Summary of Minimum Annual Lease Payments under Lease Terms (Details) Sheet http://www.coastalbank.com/role/LeasesSummaryofMinimumAnnualLeasePaymentsunderLeaseTermsDetails Leases - Summary of Minimum Annual Lease Payments under Lease Terms (Details) Details 48 false false R49.htm 9955541 - Disclosure - Leases - Summary of Components of Total Lease Expense and Operating Cash Flows (Details) Sheet http://www.coastalbank.com/role/LeasesSummaryofComponentsofTotalLeaseExpenseandOperatingCashFlowsDetails Leases - Summary of Components of Total Lease Expense and Operating Cash Flows (Details) Details 49 false false R50.htm 9955542 - Disclosure - Stock-Based Compensation - Additional Information (Details) Sheet http://www.coastalbank.com/role/StockBasedCompensationAdditionalInformationDetails Stock-Based Compensation - Additional Information (Details) Details 50 false false R51.htm 9955543 - Disclosure - Stock-Based Compensation - Summary of Stock Option Activity (Details) Sheet http://www.coastalbank.com/role/StockBasedCompensationSummaryofStockOptionActivityDetails Stock-Based Compensation - Summary of Stock Option Activity (Details) Details 51 false false R52.htm 9955544 - Disclosure - Stock-Based Compensation - Summary of Nonvested Shares (Details) Sheet http://www.coastalbank.com/role/StockBasedCompensationSummaryofNonvestedSharesDetails Stock-Based Compensation - Summary of Nonvested Shares (Details) Details 52 false false R53.htm 9955545 - Disclosure - Fair Value Measurements - Summary of Estimated Fair Values of Financial Instruments (Details) Sheet http://www.coastalbank.com/role/FairValueMeasurementsSummaryofEstimatedFairValuesofFinancialInstrumentsDetails Fair Value Measurements - Summary of Estimated Fair Values of Financial Instruments (Details) Details 53 false false R54.htm 9955546 - Disclosure - Fair Value Measurements - Summary of Assets Measured at Fair Value on Recurring Basis (Details) Sheet http://www.coastalbank.com/role/FairValueMeasurementsSummaryofAssetsMeasuredatFairValueonRecurringBasisDetails Fair Value Measurements - Summary of Assets Measured at Fair Value on Recurring Basis (Details) Details 54 false false R55.htm 9955547 - Disclosure - Fair Value Measurements - Summary of Financial Assets and Liabilities Measured at Fair Value on Nonrecurring Basis (Details) Sheet http://www.coastalbank.com/role/FairValueMeasurementsSummaryofFinancialAssetsandLiabilitiesMeasuredatFairValueonNonrecurringBasisDetails Fair Value Measurements - Summary of Financial Assets and Liabilities Measured at Fair Value on Nonrecurring Basis (Details) Details 55 false false R56.htm 9955548 - Disclosure - Fair Value Measurements - Summary of Carrying Value of Equity Securities Without Readily Determinable Fair Values (Details) Sheet http://www.coastalbank.com/role/FairValueMeasurementsSummaryofCarryingValueofEquitySecuritiesWithoutReadilyDeterminableFairValuesDetails Fair Value Measurements - Summary of Carrying Value of Equity Securities Without Readily Determinable Fair Values (Details) Details 56 false false R57.htm 9955549 - Disclosure - Fair Value Measurements - Summary of Assets and Liabilities Classified as Level 3 and Measured at Fair Value on Nonrecurring Basis (Details) Sheet http://www.coastalbank.com/role/FairValueMeasurementsSummaryofAssetsandLiabilitiesClassifiedasLevel3andMeasuredatFairValueonNonrecurringBasisDetails Fair Value Measurements - Summary of Assets and Liabilities Classified as Level 3 and Measured at Fair Value on Nonrecurring Basis (Details) Details 57 false false R58.htm 9955550 - Disclosure - Earnings Per Common Share - Schedule of Computation of Basic and Diluted Earnings Per Common Share (Details) Sheet http://www.coastalbank.com/role/EarningsPerCommonShareScheduleofComputationofBasicandDilutedEarningsPerCommonShareDetails Earnings Per Common Share - Schedule of Computation of Basic and Diluted Earnings Per Common Share (Details) Details 58 false false R59.htm 9955551 - Disclosure - Segment Reporting - Additional Information (Details) Sheet http://www.coastalbank.com/role/SegmentReportingAdditionalInformationDetails Segment Reporting - Additional Information (Details) Details 59 false false R60.htm 9955552 - Disclosure - Segment Reporting - Summary of Financial Information of Reportable Segments and Reconciliation to Consolidated Financial Results (Details) Sheet http://www.coastalbank.com/role/SegmentReportingSummaryofFinancialInformationofReportableSegmentsandReconciliationtoConsolidatedFinancialResultsDetails Segment Reporting - Summary of Financial Information of Reportable Segments and Reconciliation to Consolidated Financial Results (Details) Details 60 false false All Reports Book All Reports ck1437958-20260331.htm ck1437958-20260331.xsd ck1437958-20260331_cal.xml ck1437958-20260331_def.xml ck1437958-20260331_lab.xml ck1437958-20260331_pre.xml http://fasb.org/srt/2025 http://fasb.org/us-gaap/2025 http://xbrl.sec.gov/dei/2025 http://xbrl.sec.gov/ecd/2025 true true