3.10.0.1 html 978 862 1 false 189 0 false 9 false false R1.htm 0001000 - Document - Document and Entity Information Sheet http://ucbi.com/role/DocumentAndEntityInformation Document and Entity Information Cover 1 false false R2.htm 1001000 - Statement - Consolidated Statements of Income Sheet http://ucbi.com/role/ConsolidatedStatementsOfIncome Consolidated Statements of Income Statements 2 false false R3.htm 1002000 - Statement - Consolidated Statements of Comprehensive Income (Loss) Sheet http://ucbi.com/role/ConsolidatedStatementsOfComprehensiveIncomeLoss Consolidated Statements of Comprehensive Income (Loss) Statements 3 false false R4.htm 1003000 - Statement - Consolidated Balance Sheets Sheet http://ucbi.com/role/ConsolidatedBalanceSheets Consolidated Balance Sheets Statements 4 false false R5.htm 1003501 - Statement - Consolidated Balance Sheets (Parenthetical) Sheet http://ucbi.com/role/ConsolidatedBalanceSheetsParenthetical Consolidated Balance Sheets (Parenthetical) Statements 5 false false R6.htm 1004000 - Statement - Consolidated Statements of Changes in Shareholders' Equity Sheet http://ucbi.com/role/ConsolidatedStatementsOfChangesInShareholdersEquity Consolidated Statements of Changes in Shareholders' Equity Statements 6 false false R7.htm 1004501 - Statement - Consolidated Statements of Changes in Shareholders' Equity (Parenthetical) Sheet http://ucbi.com/role/ConsolidatedStatementsOfChangesInShareholdersEquityParenthetical Consolidated Statements of Changes in Shareholders' Equity (Parenthetical) Statements 7 false false R8.htm 1005000 - Statement - Consolidated Statements of Cash Flows Sheet http://ucbi.com/role/ConsolidatedStatementsOfCashFlows Consolidated Statements of Cash Flows Statements 8 false false R9.htm 2101100 - Disclosure - Summary of Significant Accounting Policies Sheet http://ucbi.com/role/SummaryOfSignificantAccountingPolicies Summary of Significant Accounting Policies Notes 9 false false R10.htm 2102100 - Disclosure - Accounting Standards Updates and Recently Adopted Standards Sheet http://ucbi.com/role/AccountingStandardsUpdatesAndRecentlyAdoptedStandards Accounting Standards Updates and Recently Adopted Standards Notes 10 false false R11.htm 2103100 - Disclosure - Mergers and Acquisitions Sheet http://ucbi.com/role/MergersAndAcquisitions Mergers and Acquisitions Notes 11 false false R12.htm 2104100 - Disclosure - Cash Flows Sheet http://ucbi.com/role/CashFlows Cash Flows Notes 12 false false R13.htm 2105100 - Disclosure - Balance Sheet Offsetting and Repurchase Agreements Accounted for as Secured Borrowings Sheet http://ucbi.com/role/BalanceSheetOffsettingAndRepurchaseAgreementsAccountedForAsSecuredBorrowings Balance Sheet Offsetting and Repurchase Agreements Accounted for as Secured Borrowings Notes 13 false false R14.htm 2106100 - Disclosure - Investment Securities Sheet http://ucbi.com/role/InvestmentSecurities Investment Securities Notes 14 false false R15.htm 2107100 - Disclosure - Loans and Leases and Allowance for Credit Losses Sheet http://ucbi.com/role/LoansAndLeasesAndAllowanceForCreditLosses Loans and Leases and Allowance for Credit Losses Notes 15 false false R16.htm 2108100 - Disclosure - Premises and Equipment Sheet http://ucbi.com/role/PremisesAndEquipment Premises and Equipment Notes 16 false false R17.htm 2109100 - Disclosure - Goodwill and Other Intangible Assets Sheet http://ucbi.com/role/GoodwillAndOtherIntangibleAssets Goodwill and Other Intangible Assets Notes 17 false false R18.htm 2110100 - Disclosure - Servicing Rights Sheet http://ucbi.com/role/ServicingRights Servicing Rights Notes 18 false false R19.htm 2111100 - Disclosure - Deposits Sheet http://ucbi.com/role/Deposits Deposits Notes 19 false false R20.htm 2112100 - Disclosure - Federal Home Loan Bank Advances Sheet http://ucbi.com/role/FederalHomeLoanBankAdvances Federal Home Loan Bank Advances Notes 20 false false R21.htm 2113100 - Disclosure - Long-term Debt Sheet http://ucbi.com/role/LongTermDebt Long-term Debt Notes 21 false false R22.htm 2114100 - Disclosure - Reclassifications Out of Accumulated Other Comprehensive Income Sheet http://ucbi.com/role/ReclassificationsOutOfAccumulatedOtherComprehensiveIncome Reclassifications Out of Accumulated Other Comprehensive Income Notes 22 false false R23.htm 2115100 - Disclosure - Earnings Per Share Sheet http://ucbi.com/role/EarningsPerShare Earnings Per Share Notes 23 false false R24.htm 2116100 - Disclosure - Income Taxes Sheet http://ucbi.com/role/IncomeTaxes Income Taxes Notes 24 false false R25.htm 2117100 - Disclosure - Pension and Employee Benefit Plans Sheet http://ucbi.com/role/PensionAndEmployeeBenefitPlans Pension and Employee Benefit Plans Notes 25 false false R26.htm 2118100 - Disclosure - Derivatives and Hedging Activities Sheet http://ucbi.com/role/DerivativesAndHedgingActivities Derivatives and Hedging Activities Notes 26 false false R27.htm 2119100 - Disclosure - Regulatory Matters Sheet http://ucbi.com/role/RegulatoryMatters Regulatory Matters Notes 27 false false R28.htm 2120100 - Disclosure - Commitments and Contingencies Sheet http://ucbi.com/role/CommitmentsAndContingencies Commitments and Contingencies Notes 28 false false R29.htm 2121100 - Disclosure - Common and Preferred Stock Sheet http://ucbi.com/role/CommonAndPreferredStock Common and Preferred Stock Notes 29 false false R30.htm 2122100 - Disclosure - Equity Compensation and Related Plans Sheet http://ucbi.com/role/EquityCompensationAndRelatedPlans Equity Compensation and Related Plans Notes 30 false false R31.htm 2123100 - Disclosure - Assets and Liabilities Measured at Fair Value Sheet http://ucbi.com/role/AssetsAndLiabilitiesMeasuredAtFairValue Assets and Liabilities Measured at Fair Value Notes 31 false false R32.htm 2124100 - Disclosure - Condensed Financial Statements of United Community Banks, Inc. (Parent Only) Sheet http://ucbi.com/role/CondensedFinancialStatementsOfUnitedCommunityBanksIncParentOnly Condensed Financial Statements of United Community Banks, Inc. (Parent Only) Notes 32 false false R33.htm 2125100 - Disclosure - Subsequent Events Sheet http://ucbi.com/role/SubsequentEvents Subsequent Events Notes 33 false false R34.htm 2201201 - Disclosure - Summary of Significant Accounting Policies (Policies) Sheet http://ucbi.com/role/SummaryOfSignificantAccountingPoliciesPolicies Summary of Significant Accounting Policies (Policies) Policies http://ucbi.com/role/SummaryOfSignificantAccountingPolicies 34 false false R35.htm 2303301 - Disclosure - Mergers and Acquisitions (Tables) Sheet http://ucbi.com/role/MergersAndAcquisitionsTables Mergers and Acquisitions (Tables) Tables http://ucbi.com/role/MergersAndAcquisitions 35 false false R36.htm 2305301 - Disclosure - Balance Sheet Offsetting and Repurchase Agreements Accounted for as Secured Borrowings (Tables) Sheet http://ucbi.com/role/BalanceSheetOffsettingAndRepurchaseAgreementsAccountedForAsSecuredBorrowingsTables Balance Sheet Offsetting and Repurchase Agreements Accounted for as Secured Borrowings (Tables) Tables http://ucbi.com/role/BalanceSheetOffsettingAndRepurchaseAgreementsAccountedForAsSecuredBorrowings 36 false false R37.htm 2306301 - Disclosure - Investment Securities (Tables) Sheet http://ucbi.com/role/InvestmentSecuritiesTables Investment Securities (Tables) Tables http://ucbi.com/role/InvestmentSecurities 37 false false R38.htm 2307301 - Disclosure - Loans and Leases and Allowance for Credit Losses (Tables) Sheet http://ucbi.com/role/LoansAndLeasesAndAllowanceForCreditLossesTables Loans and Leases and Allowance for Credit Losses (Tables) Tables http://ucbi.com/role/LoansAndLeasesAndAllowanceForCreditLosses 38 false false R39.htm 2308301 - Disclosure - Premises and Equipment (Tables) Sheet http://ucbi.com/role/PremisesAndEquipmentTables Premises and Equipment (Tables) Tables http://ucbi.com/role/PremisesAndEquipment 39 false false R40.htm 2309301 - Disclosure - Goodwill and Other Intangible Assets (Tables) Sheet http://ucbi.com/role/GoodwillAndOtherIntangibleAssetsTables Goodwill and Other Intangible Assets (Tables) Tables http://ucbi.com/role/GoodwillAndOtherIntangibleAssets 40 false false R41.htm 2310301 - Disclosure - Servicing Rights (Tables) Sheet http://ucbi.com/role/ServicingRightsTables Servicing Rights (Tables) Tables http://ucbi.com/role/ServicingRights 41 false false R42.htm 2311301 - Disclosure - Deposits (Tables) Sheet http://ucbi.com/role/DepositsTables Deposits (Tables) Tables http://ucbi.com/role/Deposits 42 false false R43.htm 2312301 - Disclosure - Federal Home Loan Bank Advances (Tables) Sheet http://ucbi.com/role/FederalHomeLoanBankAdvancesTables Federal Home Loan Bank Advances (Tables) Tables http://ucbi.com/role/FederalHomeLoanBankAdvances 43 false false R44.htm 2313301 - Disclosure - Long-term Debt (Tables) Sheet http://ucbi.com/role/LongTermDebtTables Long-term Debt (Tables) Tables http://ucbi.com/role/LongTermDebt 44 false false R45.htm 2314301 - Disclosure - Reclassifications Out of Accumulated Other Comprehensive Income (Tables) Sheet http://ucbi.com/role/ReclassificationsOutOfAccumulatedOtherComprehensiveIncomeTables Reclassifications Out of Accumulated Other Comprehensive Income (Tables) Tables http://ucbi.com/role/ReclassificationsOutOfAccumulatedOtherComprehensiveIncome 45 false false R46.htm 2315301 - Disclosure - Earnings Per Share (Tables) Sheet http://ucbi.com/role/EarningsPerShareTables Earnings Per Share (Tables) Tables http://ucbi.com/role/EarningsPerShare 46 false false R47.htm 2316301 - Disclosure - Income Taxes (Tables) Sheet http://ucbi.com/role/IncomeTaxesTables Income Taxes (Tables) Tables http://ucbi.com/role/IncomeTaxes 47 false false R48.htm 2317301 - Disclosure - Pension and Employee Benefit Plans (Tables) Sheet http://ucbi.com/role/PensionAndEmployeeBenefitPlansTables Pension and Employee Benefit Plans (Tables) Tables http://ucbi.com/role/PensionAndEmployeeBenefitPlans 48 false false R49.htm 2318301 - Disclosure - Derivatives and Hedging Activities (Tables) Sheet http://ucbi.com/role/DerivativesAndHedgingActivitiesTables Derivatives and Hedging Activities (Tables) Tables http://ucbi.com/role/DerivativesAndHedgingActivities 49 false false R50.htm 2319301 - Disclosure - Regulatory Matters (Tables) Sheet http://ucbi.com/role/RegulatoryMattersTables Regulatory Matters (Tables) Tables http://ucbi.com/role/RegulatoryMatters 50 false false R51.htm 2320301 - Disclosure - Commitments and Contingencies (Tables) Sheet http://ucbi.com/role/CommitmentsAndContingenciesTables Commitments and Contingencies (Tables) Tables http://ucbi.com/role/CommitmentsAndContingencies 51 false false R52.htm 2322301 - Disclosure - Equity Compensation and Related Plans (Tables) Sheet http://ucbi.com/role/EquityCompensationAndRelatedPlansTables Equity Compensation and Related Plans (Tables) Tables http://ucbi.com/role/EquityCompensationAndRelatedPlans 52 false false R53.htm 2323301 - Disclosure - Assets and Liabilities Measured at Fair Value (Tables) Sheet http://ucbi.com/role/AssetsAndLiabilitiesMeasuredAtFairValueTables Assets and Liabilities Measured at Fair Value (Tables) Tables http://ucbi.com/role/AssetsAndLiabilitiesMeasuredAtFairValue 53 false false R54.htm 2324301 - Disclosure - Condensed Financial Statements of United Community Banks, Inc. (Parent Only) (Tables) Sheet http://ucbi.com/role/CondensedFinancialStatementsOfUnitedCommunityBanksIncParentOnlyTables Condensed Financial Statements of United Community Banks, Inc. (Parent Only) (Tables) Tables http://ucbi.com/role/CondensedFinancialStatementsOfUnitedCommunityBanksIncParentOnly 54 false false R55.htm 2401402 - Disclosure - Summary of Significant Accounting Policies - Narrative (Details) Sheet http://ucbi.com/role/SummaryOfSignificantAccountingPoliciesNarrativeDetails Summary of Significant Accounting Policies - Narrative (Details) Details 55 false false R56.htm 2402401 - Disclosure - Accounting Standards Updates and Recently Adopted Standards - Narrative (Details) Sheet http://ucbi.com/role/AccountingStandardsUpdatesAndRecentlyAdoptedStandardsNarrativeDetails Accounting Standards Updates and Recently Adopted Standards - Narrative (Details) Details http://ucbi.com/role/AccountingStandardsUpdatesAndRecentlyAdoptedStandards 56 false false R57.htm 2403402 - Disclosure - Mergers and Acquisitions - Acquisition date fair value of purchased assets and liabilities (Details) Sheet http://ucbi.com/role/MergersAndAcquisitionsAcquisitionDateFairValueOfPurchasedAssetsAndLiabilitiesDetails Mergers and Acquisitions - Acquisition date fair value of purchased assets and liabilities (Details) Details 57 false false R58.htm 2403403 - Disclosure - Mergers and Acquisitions - Acquired loan and lease asset portfolio at acquisition date (Details) Sheet http://ucbi.com/role/MergersAndAcquisitionsAcquiredLoanAndLeaseAssetPortfolioAtAcquisitionDateDetails Mergers and Acquisitions - Acquired loan and lease asset portfolio at acquisition date (Details) Details 58 false false R59.htm 2403404 - Disclosure - Mergers and Acquisitions - Pro forma information (Details) Sheet http://ucbi.com/role/MergersAndAcquisitionsProFormaInformationDetails Mergers and Acquisitions - Pro forma information (Details) Details 59 false false R60.htm 2403405 - Disclosure - Mergers and Acquisitions - Narrative (Details) Sheet http://ucbi.com/role/MergersAndAcquisitionsNarrativeDetails Mergers and Acquisitions - Narrative (Details) Details 60 false false R61.htm 2404401 - Disclosure - Cash Flows - Narrative (Details) Sheet http://ucbi.com/role/CashFlowsNarrativeDetails Cash Flows - Narrative (Details) Details 61 false false R62.htm 2405402 - Disclosure - Balance Sheet Offsetting and Repurchase Agreements Accounted for as Secured Borrowings - Summary of amounts outstanding under master netting agreements (Details) Sheet http://ucbi.com/role/BalanceSheetOffsettingAndRepurchaseAgreementsAccountedForAsSecuredBorrowingsSummaryOfAmountsOutstandingUnderMasterNettingAgreementsDetails Balance Sheet Offsetting and Repurchase Agreements Accounted for as Secured Borrowings - Summary of amounts outstanding under master netting agreements (Details) Details 62 false false R63.htm 2405403 - Disclosure - Balance Sheet Offsetting and Repurchase Agreements Accounted for as Secured Borrowings - Narrative (Details) Sheet http://ucbi.com/role/BalanceSheetOffsettingAndRepurchaseAgreementsAccountedForAsSecuredBorrowingsNarrativeDetails Balance Sheet Offsetting and Repurchase Agreements Accounted for as Secured Borrowings - Narrative (Details) Details http://ucbi.com/role/BalanceSheetOffsettingAndRepurchaseAgreementsAccountedForAsSecuredBorrowingsTables 63 false false R64.htm 2405404 - Disclosure - Balance Sheet Offsetting and Repurchase Agreements Accounted for as Secured Borrowings - Repurchase agreements accounted for as secured borrowings (Details) Sheet http://ucbi.com/role/BalanceSheetOffsettingAndRepurchaseAgreementsAccountedForAsSecuredBorrowingsRepurchaseAgreementsAccountedForAsSecuredBorrowingsDetails Balance Sheet Offsetting and Repurchase Agreements Accounted for as Secured Borrowings - Repurchase agreements accounted for as secured borrowings (Details) Details 64 false false R65.htm 2406402 - Disclosure - Investment Securities - Cost basis, unrealized gains and losses, and fair value of debt securities held to maturity (Details) Sheet http://ucbi.com/role/InvestmentSecuritiesCostBasisUnrealizedGainsAndLossesAndFairValueOfDebtSecuritiesHeldToMaturityDetails Investment Securities - Cost basis, unrealized gains and losses, and fair value of debt securities held to maturity (Details) Details 65 false false R66.htm 2406403 - Disclosure - Investment Securities - Cost basis, unrealized gains and losses, and fair value of debt securities available for sale (Details) Sheet http://ucbi.com/role/InvestmentSecuritiesCostBasisUnrealizedGainsAndLossesAndFairValueOfDebtSecuritiesAvailableForSaleDetails Investment Securities - Cost basis, unrealized gains and losses, and fair value of debt securities available for sale (Details) Details 66 false false R67.htm 2406404 - Disclosure - Investment Securities - Summary of held-to-maturity securities in unrealized loss position (Details) Sheet http://ucbi.com/role/InvestmentSecuritiesSummaryOfHeldToMaturitySecuritiesInUnrealizedLossPositionDetails Investment Securities - Summary of held-to-maturity securities in unrealized loss position (Details) Details 67 false false R68.htm 2406405 - Disclosure - Investment Securities - Summary of available-for-sale securities in unrealized loss position (Details) Sheet http://ucbi.com/role/InvestmentSecuritiesSummaryOfAvailableForSaleSecuritiesInUnrealizedLossPositionDetails Investment Securities - Summary of available-for-sale securities in unrealized loss position (Details) Details 68 false false R69.htm 2406406 - Disclosure - Investment Securities - Summary of securities sales activity (Details) Sheet http://ucbi.com/role/InvestmentSecuritiesSummaryOfSecuritiesSalesActivityDetails Investment Securities - Summary of securities sales activity (Details) Details 69 false false R70.htm 2406407 - Disclosure - Investment Securities - Amortized cost and fair value of held-to-maturity and available-for-sale securities by contractual maturity (Details) Sheet http://ucbi.com/role/InvestmentSecuritiesAmortizedCostAndFairValueOfHeldToMaturityAndAvailableForSaleSecuritiesByContractualMaturityDetails Investment Securities - Amortized cost and fair value of held-to-maturity and available-for-sale securities by contractual maturity (Details) Details 70 false false R71.htm 2406408 - Disclosure - Investment Securities - Narrative (Details) Sheet http://ucbi.com/role/InvestmentSecuritiesNarrativeDetails Investment Securities - Narrative (Details) Details 71 false false R72.htm 2407402 - Disclosure - Loans and Leases and Allowance for Credit Losses - Major classifications of loans and lease portfolio (Details) Sheet http://ucbi.com/role/LoansAndLeasesAndAllowanceForCreditLossesMajorClassificationsOfLoansAndLeasePortfolioDetails Loans and Leases and Allowance for Credit Losses - Major classifications of loans and lease portfolio (Details) Details 72 false false R73.htm 2407403 - Disclosure - Loans and Leases and Allowance for Credit Losses - Changes in the value of the accretable yield for PCI loans (Details) Sheet http://ucbi.com/role/LoansAndLeasesAndAllowanceForCreditLossesChangesInValueOfAccretableYieldForPciLoansDetails Loans and Leases and Allowance for Credit Losses - Changes in the value of the accretable yield for PCI loans (Details) Details 73 false false R74.htm 2407404 - Disclosure - Loans and Leases and Allowance for Credit Losses - Components of net investment in leases (Details) Sheet http://ucbi.com/role/LoansAndLeasesAndAllowanceForCreditLossesComponentsOfNetInvestmentInLeasesDetails Loans and Leases and Allowance for Credit Losses - Components of net investment in leases (Details) Details 74 false false R75.htm 2407405 - Disclosure - Loans and Leases and Allowance for Credit Losses - Minimum future lease payments to be received (Details) Sheet http://ucbi.com/role/LoansAndLeasesAndAllowanceForCreditLossesMinimumFutureLeasePaymentsToBeReceivedDetails Loans and Leases and Allowance for Credit Losses - Minimum future lease payments to be received (Details) Details 75 false false R76.htm 2407406 - Disclosure - Loans and Leases and Allowance for Credit Losses - Bank loans granted to executive officers and directors (Details) Sheet http://ucbi.com/role/LoansAndLeasesAndAllowanceForCreditLossesBankLoansGrantedToExecutiveOfficersAndDirectorsDetails Loans and Leases and Allowance for Credit Losses - Bank loans granted to executive officers and directors (Details) Details 76 false false R77.htm 2407407 - Disclosure - Loans and Leases and Allowance for Credit Losses - Balance and activity in allowance for credit losses by portfolio segment (Details) Sheet http://ucbi.com/role/LoansAndLeasesAndAllowanceForCreditLossesBalanceAndActivityInAllowanceForCreditLossesByPortfolioSegmentDetails Loans and Leases and Allowance for Credit Losses - Balance and activity in allowance for credit losses by portfolio segment (Details) Details 77 false false R78.htm 2407408 - Disclosure - Loans and Leases and Allowance for Credit Losses - Recorded investment in loans by portfolio segment and the balance of the allowance for loan losses (Details) Sheet http://ucbi.com/role/LoansAndLeasesAndAllowanceForCreditLossesRecordedInvestmentInLoansByPortfolioSegmentAndBalanceOfAllowanceForLoanLossesDetails Loans and Leases and Allowance for Credit Losses - Recorded investment in loans by portfolio segment and the balance of the allowance for loan losses (Details) Details 78 false false R79.htm 2407409 - Disclosure - Loans and Leases and Allowance for Credit Losses - Loans individually evaluated for impairment by class of loans (Details) Sheet http://ucbi.com/role/LoansAndLeasesAndAllowanceForCreditLossesLoansIndividuallyEvaluatedForImpairmentByClassOfLoansDetails Loans and Leases and Allowance for Credit Losses - Loans individually evaluated for impairment by class of loans (Details) Details 79 false false R80.htm 2407410 - Disclosure - Loans and Leases and Allowance for Credit Losses - Loans modified under terms of TDR (Details) Sheet http://ucbi.com/role/LoansAndLeasesAndAllowanceForCreditLossesLoansModifiedUnderTermsOfTdrDetails Loans and Leases and Allowance for Credit Losses - Loans modified under terms of TDR (Details) Details 80 false false R81.htm 2407411 - Disclosure - Loans and Leases and Allowance for Credit Losses - Average balances of impaired loans and income recognized on impaired loans (Details) Sheet http://ucbi.com/role/LoansAndLeasesAndAllowanceForCreditLossesAverageBalancesOfImpairedLoansAndIncomeRecognizedOnImpairedLoansDetails Loans and Leases and Allowance for Credit Losses - Average balances of impaired loans and income recognized on impaired loans (Details) Details 81 false false R82.htm 2407412 - Disclosure - Loans and Leases and Allowance for Credit Losses - Recorded investment in nonaccrual loans by loan class (Details) Sheet http://ucbi.com/role/LoansAndLeasesAndAllowanceForCreditLossesRecordedInvestmentInNonaccrualLoansByLoanClassDetails Loans and Leases and Allowance for Credit Losses - Recorded investment in nonaccrual loans by loan class (Details) Details 82 false false R83.htm 2407413 - Disclosure - Loans and Leases and Allowance for Credit Losses - Aging of recorded investment in past due loans (Details) Sheet http://ucbi.com/role/LoansAndLeasesAndAllowanceForCreditLossesAgingOfRecordedInvestmentInPastDueLoansDetails Loans and Leases and Allowance for Credit Losses - Aging of recorded investment in past due loans (Details) Details 83 false false R84.htm 2407414 - Disclosure - Loans and Leases and Allowance for Credit Losses - Risk category of loans by class of loans (Details) Sheet http://ucbi.com/role/LoansAndLeasesAndAllowanceForCreditLossesRiskCategoryOfLoansByClassOfLoansDetails Loans and Leases and Allowance for Credit Losses - Risk category of loans by class of loans (Details) Details 84 false false R85.htm 2407415 - Disclosure - Loans and Leases and Allowance for Credit Losses - Narrative (Details) Sheet http://ucbi.com/role/LoansAndLeasesAndAllowanceForCreditLossesNarrativeDetails Loans and Leases and Allowance for Credit Losses - Narrative (Details) Details http://ucbi.com/role/LoansAndLeasesAndAllowanceForCreditLossesTables 85 false false R86.htm 2408402 - Disclosure - Premises and Equipment - Summary (Details) Sheet http://ucbi.com/role/PremisesAndEquipmentSummaryDetails Premises and Equipment - Summary (Details) Details 86 false false R87.htm 2408403 - Disclosure - Premises and Equipment - Rent commitments under operating leases (Details) Sheet http://ucbi.com/role/PremisesAndEquipmentRentCommitmentsUnderOperatingLeasesDetails Premises and Equipment - Rent commitments under operating leases (Details) Details 87 false false R88.htm 2408404 - Disclosure - Premises and Equipment - Narrative (Details) Sheet http://ucbi.com/role/PremisesAndEquipmentNarrativeDetails Premises and Equipment - Narrative (Details) Details 88 false false R89.htm 2409402 - Disclosure - Goodwill and Other Intangible Assets - Summary (Details) Sheet http://ucbi.com/role/GoodwillAndOtherIntangibleAssetsSummaryDetails Goodwill and Other Intangible Assets - Summary (Details) Details 89 false false R90.htm 2409403 - Disclosure - Goodwill and Other Intangible Assets - Changes in carrying amounts of goodwill (Details) Sheet http://ucbi.com/role/GoodwillAndOtherIntangibleAssetsChangesInCarryingAmountsOfGoodwillDetails Goodwill and Other Intangible Assets - Changes in carrying amounts of goodwill (Details) Details 90 false false R91.htm 2409404 - Disclosure - Goodwill and Other Intangible Assets - Estimated aggregate amortization expense for future periods (Details) Sheet http://ucbi.com/role/GoodwillAndOtherIntangibleAssetsEstimatedAggregateAmortizationExpenseForFuturePeriodsDetails Goodwill and Other Intangible Assets - Estimated aggregate amortization expense for future periods (Details) Details 91 false false R92.htm 2410402 - Disclosure - Servicing Rights - Changes in SBA/USDA loans servicing rights (Details) Sheet http://ucbi.com/role/ServicingRightsChangesInSbaUsdaLoansServicingRightsDetails Servicing Rights - Changes in SBA/USDA loans servicing rights (Details) Details 92 false false R93.htm 2410403 - Disclosure - Servicing Rights - Key characteristics, inputs, and economic assumptions for SBA/USDA loans and related sensitivity (Details) Sheet http://ucbi.com/role/ServicingRightsKeyCharacteristicsInputsAndEconomicAssumptionsForSbaUsdaLoansAndRelatedSensitivityDetails Servicing Rights - Key characteristics, inputs, and economic assumptions for SBA/USDA loans and related sensitivity (Details) Details 93 false false R94.htm 2410404 - Disclosure - Servicing Rights - Changes in residential mortgage loans servicing rights (Details) Sheet http://ucbi.com/role/ServicingRightsChangesInResidentialMortgageLoansServicingRightsDetails Servicing Rights - Changes in residential mortgage loans servicing rights (Details) Details 94 false false R95.htm 2410405 - Disclosure - Servicing Rights - Valuation allowance for impairment of residential mortgage servicing rights portfolio (Details) Sheet http://ucbi.com/role/ServicingRightsValuationAllowanceForImpairmentOfResidentialMortgageServicingRightsPortfolioDetails Servicing Rights - Valuation allowance for impairment of residential mortgage servicing rights portfolio (Details) Details 95 false false R96.htm 2410406 - Disclosure - Servicing Rights - Key characteristics, inputs, and economic assumptions for residential mortgage loans and related sensitivity (Details) Sheet http://ucbi.com/role/ServicingRightsKeyCharacteristicsInputsAndEconomicAssumptionsForResidentialMortgageLoansAndRelatedSensitivityDetails Servicing Rights - Key characteristics, inputs, and economic assumptions for residential mortgage loans and related sensitivity (Details) Details 96 false false R97.htm 2410407 - Disclosure - Servicing Rights - Narrative (Details) Sheet http://ucbi.com/role/ServicingRightsNarrativeDetails Servicing Rights - Narrative (Details) Details 97 false false R98.htm 2411402 - Disclosure - Deposits - Contractual maturities of time deposits (Details) Sheet http://ucbi.com/role/DepositsContractualMaturitiesOfTimeDepositsDetails Deposits - Contractual maturities of time deposits (Details) Details 98 false false R99.htm 2411403 - Disclosure - Deposits - Narrative (Details) Sheet http://ucbi.com/role/DepositsNarrativeDetails Deposits - Narrative (Details) Details 99 false false R100.htm 2412402 - Disclosure - Federal Home Loan Bank Advances - Maturities and current rates of outstanding advances (Details) Sheet http://ucbi.com/role/FederalHomeLoanBankAdvancesMaturitiesAndCurrentRatesOfOutstandingAdvancesDetails Federal Home Loan Bank Advances - Maturities and current rates of outstanding advances (Details) Details 100 false false R101.htm 2412403 - Disclosure - Federal Home Loan Bank Advances - Narrative (Details) Sheet http://ucbi.com/role/FederalHomeLoanBankAdvancesNarrativeDetails Federal Home Loan Bank Advances - Narrative (Details) Details 101 false false R102.htm 2413402 - Disclosure - Long-term Debt - Schedule of long-term debt (Details) Sheet http://ucbi.com/role/LongTermDebtScheduleOfLongTermDebtDetails Long-term Debt - Schedule of long-term debt (Details) Details 102 false false R103.htm 2413403 - Disclosure - Long-term Debt - Narrative (Details) Sheet http://ucbi.com/role/LongTermDebtNarrativeDetails Long-term Debt - Narrative (Details) Details 103 false false R104.htm 2414402 - Disclosure - Reclassifications Out of Accumulated Other Comprehensive Income - Summary of reclassifications (Details) Sheet http://ucbi.com/role/ReclassificationsOutOfAccumulatedOtherComprehensiveIncomeSummaryOfReclassificationsDetails Reclassifications Out of Accumulated Other Comprehensive Income - Summary of reclassifications (Details) Details 104 false false R105.htm 2415402 - Disclosure - Earnings Per Share - Computation of basic and diluted earnings per share (Details) Sheet http://ucbi.com/role/EarningsPerShareComputationOfBasicAndDilutedEarningsPerShareDetails Earnings Per Share - Computation of basic and diluted earnings per share (Details) Details 105 false false R106.htm 2415403 - Disclosure - Earnings Per Share - Narrative (Details) Sheet http://ucbi.com/role/EarningsPerShareNarrativeDetails Earnings Per Share - Narrative (Details) Details 106 false false R107.htm 2416402 - Disclosure - Income Taxes - Income tax expense (Details) Sheet http://ucbi.com/role/IncomeTaxesIncomeTaxExpenseDetails Income Taxes - Income tax expense (Details) Details 107 false false R108.htm 2416403 - Disclosure - Income Taxes - Differences between provision for income taxes and amount computed as statutory rate (Details) Sheet http://ucbi.com/role/IncomeTaxesDifferencesBetweenProvisionForIncomeTaxesAndAmountComputedAsStatutoryRateDetails Income Taxes - Differences between provision for income taxes and amount computed as statutory rate (Details) Details 108 false false R109.htm 2416404 - Disclosure - Income Taxes - Deferred taxes (Details) Sheet http://ucbi.com/role/IncomeTaxesDeferredTaxesDetails Income Taxes - Deferred taxes (Details) Details 109 false false R110.htm 2416405 - Disclosure - Income Taxes - Reconciliation of unrecognized tax benefits (Details) Sheet http://ucbi.com/role/IncomeTaxesReconciliationOfUnrecognizedTaxBenefitsDetails Income Taxes - Reconciliation of unrecognized tax benefits (Details) Details 110 false false R111.htm 2416406 - Disclosure - Income Taxes - Narrative (Details) Sheet http://ucbi.com/role/IncomeTaxesNarrativeDetails Income Taxes - Narrative (Details) Details 111 false false R112.htm 2417402 - Disclosure - Pension and Employee Benefit Plans - Weighted-average assumptions to determine pension benefit obligation (Details) Sheet http://ucbi.com/role/PensionAndEmployeeBenefitPlansWeightedAverageAssumptionsToDeterminePensionBenefitObligationDetails Pension and Employee Benefit Plans - Weighted-average assumptions to determine pension benefit obligation (Details) Details 112 false false R113.htm 2417403 - Disclosure - Pension and Employee Benefit Plans - Changes in obligations and plan assets (Details) Sheet http://ucbi.com/role/PensionAndEmployeeBenefitPlansChangesInObligationsAndPlanAssetsDetails Pension and Employee Benefit Plans - Changes in obligations and plan assets (Details) Details 113 false false R114.htm 2417404 - Disclosure - Pension and Employee Benefit Plans - Components of net periodic benefit cost (Details) Sheet http://ucbi.com/role/PensionAndEmployeeBenefitPlansComponentsOfNetPeriodicBenefitCostDetails Pension and Employee Benefit Plans - Components of net periodic benefit cost (Details) Details 114 false false R115.htm 2417405 - Disclosure - Pension and Employee Benefit Plans - Estimated future benefit payments expected to be paid (Details) Sheet http://ucbi.com/role/PensionAndEmployeeBenefitPlansEstimatedFutureBenefitPaymentsExpectedToBePaidDetails Pension and Employee Benefit Plans - Estimated future benefit payments expected to be paid (Details) Details 115 false false R116.htm 2417406 - Disclosure - Pension and Employee Benefit Plans - Fair value of Funded Plan assets by major category (Details) Sheet http://ucbi.com/role/PensionAndEmployeeBenefitPlansFairValueOfFundedPlanAssetsByMajorCategoryDetails Pension and Employee Benefit Plans - Fair value of Funded Plan assets by major category (Details) Details 116 false false R117.htm 2417407 - Disclosure - Pension and Employee Benefit Plans - Narrative (Details) Sheet http://ucbi.com/role/PensionAndEmployeeBenefitPlansNarrativeDetails Pension and Employee Benefit Plans - Narrative (Details) Details 117 false false R118.htm 2418402 - Disclosure - Derivatives and Hedging Activities - Derivatives designated as hedge instruments under ASC 815 (Details) Sheet http://ucbi.com/role/DerivativesAndHedgingActivitiesDerivativesDesignatedAsHedgeInstrumentsUnderAsc815Details Derivatives and Hedging Activities - Derivatives designated as hedge instruments under ASC 815 (Details) Details 118 false false R119.htm 2418403 - Disclosure - Derivatives and Hedging Activities - Derivatives not designated as hedging instruments under ASC 815 (Details) Sheet http://ucbi.com/role/DerivativesAndHedgingActivitiesDerivativesNotDesignatedAsHedgingInstrumentsUnderAsc815Details Derivatives and Hedging Activities - Derivatives not designated as hedging instruments under ASC 815 (Details) Details 119 false false R120.htm 2418404 - Disclosure - Derivatives and Hedging Activities - Effect of cash flow hedges (Details) Sheet http://ucbi.com/role/DerivativesAndHedgingActivitiesEffectOfCashFlowHedgesDetails Derivatives and Hedging Activities - Effect of cash flow hedges (Details) Details 120 false false R121.htm 2418405 - Disclosure - Derivatives and Hedging Activities - Effect of derivatives in fair value hedging relationships (Details) Sheet http://ucbi.com/role/DerivativesAndHedgingActivitiesEffectOfDerivativesInFairValueHedgingRelationshipsDetails Derivatives and Hedging Activities - Effect of derivatives in fair value hedging relationships (Details) Details 121 false false R122.htm 2418406 - Disclosure - Derivatives and Hedging Activities - Gains and losses recognized on derivatives not designated as hedging instruments under ASC 815 (Details) Sheet http://ucbi.com/role/DerivativesAndHedgingActivitiesGainsAndLossesRecognizedOnDerivativesNotDesignatedAsHedgingInstrumentsUnderAsc815Details Derivatives and Hedging Activities - Gains and losses recognized on derivatives not designated as hedging instruments under ASC 815 (Details) Details 122 false false R123.htm 2418407 - Disclosure - Derivatives and Hedging Activities - Narrative (Details) Sheet http://ucbi.com/role/DerivativesAndHedgingActivitiesNarrativeDetails Derivatives and Hedging Activities - Narrative (Details) Details 123 false false R124.htm 2419402 - Disclosure - Regulatory Matters - Regulatory capital ratios and minimum amounts required (Details) Sheet http://ucbi.com/role/RegulatoryMattersRegulatoryCapitalRatiosAndMinimumAmountsRequiredDetails Regulatory Matters - Regulatory capital ratios and minimum amounts required (Details) Details 124 false false R125.htm 2419403 - Disclosure - Regulatory Matters - Narrative (Details) Sheet http://ucbi.com/role/RegulatoryMattersNarrativeDetails Regulatory Matters - Narrative (Details) Details 125 false false R126.htm 2420402 - Disclosure - Commitments and Contingencies - Contractual amount of off-balance sheet instruments (Details) Sheet http://ucbi.com/role/CommitmentsAndContingenciesContractualAmountOfOffBalanceSheetInstrumentsDetails Commitments and Contingencies - Contractual amount of off-balance sheet instruments (Details) Details 126 false false R127.htm 2420403 - Disclosure - Commitments and Contingencies - Narrative (Details) Sheet http://ucbi.com/role/CommitmentsAndContingenciesNarrativeDetails Commitments and Contingencies - Narrative (Details) Details 127 false false R128.htm 2421401 - Disclosure - Common and Preferred Stock - Narrative (Details) Sheet http://ucbi.com/role/CommonAndPreferredStockNarrativeDetails Common and Preferred Stock - Narrative (Details) Details 128 false false R129.htm 2422402 - Disclosure - Equity Compensation and Related Plans - Restricted stock and stock option activity (Details) Sheet http://ucbi.com/role/EquityCompensationAndRelatedPlansRestrictedStockAndStockOptionActivityDetails Equity Compensation and Related Plans - Restricted stock and stock option activity (Details) Details 129 false false R130.htm 2422403 - Disclosure - Equity Compensation and Related Plans - Summary of stock options (Details) Sheet http://ucbi.com/role/EquityCompensationAndRelatedPlansSummaryOfStockOptionsDetails Equity Compensation and Related Plans - Summary of stock options (Details) Details 130 false false R131.htm 2422404 - Disclosure - Equity Compensation and Related Plans - Narrative (Details) Sheet http://ucbi.com/role/EquityCompensationAndRelatedPlansNarrativeDetails Equity Compensation and Related Plans - Narrative (Details) Details 131 false false R132.htm 2423402 - Disclosure - Assets and Liabilities Measured at Fair Value - Assets and liabilities measured at fair value on recurring basis (Details) Sheet http://ucbi.com/role/AssetsAndLiabilitiesMeasuredAtFairValueAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails Assets and Liabilities Measured at Fair Value - Assets and liabilities measured at fair value on recurring basis (Details) Details 132 false false R133.htm 2423403 - Disclosure - Assets and Liabilities Measured at Fair Value - Reconciliation for measurements at fair value on a recurring basis using significant unobservable inputs (Details) Sheet http://ucbi.com/role/AssetsAndLiabilitiesMeasuredAtFairValueReconciliationForMeasurementsAtFairValueOnRecurringBasisUsingSignificantUnobservableInputsDetails Assets and Liabilities Measured at Fair Value - Reconciliation for measurements at fair value on a recurring basis using significant unobservable inputs (Details) Details 133 false false R134.htm 2423404 - Disclosure - Assets and Liabilities Measured at Fair Value - Quantitative information about Level 3 measurements for fair value on a recurring basis (Details) Sheet http://ucbi.com/role/AssetsAndLiabilitiesMeasuredAtFairValueQuantitativeInformationAboutLevel3MeasurementsForFairValueOnRecurringBasisDetails Assets and Liabilities Measured at Fair Value - Quantitative information about Level 3 measurements for fair value on a recurring basis (Details) Details 134 false false R135.htm 2423405 - Disclosure - Assets and Liabilities Measured at Fair Value - Assets and liabilities measured at fair value on nonrecurring basis (Details) Sheet http://ucbi.com/role/AssetsAndLiabilitiesMeasuredAtFairValueAssetsAndLiabilitiesMeasuredAtFairValueOnNonrecurringBasisDetails Assets and Liabilities Measured at Fair Value - Assets and liabilities measured at fair value on nonrecurring basis (Details) Details 135 false false R136.htm 2423406 - Disclosure - Assets and Liabilities Measured at Fair Value - Fair values for other financial instruments that are not measured at fair value on recurring basis (Details) Sheet http://ucbi.com/role/AssetsAndLiabilitiesMeasuredAtFairValueFairValuesForOtherFinancialInstrumentsThatAreNotMeasuredAtFairValueOnRecurringBasisDetails Assets and Liabilities Measured at Fair Value - Fair values for other financial instruments that are not measured at fair value on recurring basis (Details) Details 136 false false R137.htm 2423407 - Disclosure - Assets and Liabilities Measured at Fair Value - Narrative (Details) Sheet http://ucbi.com/role/AssetsAndLiabilitiesMeasuredAtFairValueNarrativeDetails Assets and Liabilities Measured at Fair Value - Narrative (Details) Details 137 false false R138.htm 2424402 - Disclosure - Condensed Financial Statements of United Community Banks, Inc. (Parent Only) - Statements of Income (Details) Sheet http://ucbi.com/role/CondensedFinancialStatementsOfUnitedCommunityBanksIncParentOnlyStatementsOfIncomeDetails Condensed Financial Statements of United Community Banks, Inc. (Parent Only) - Statements of Income (Details) Details http://ucbi.com/role/CondensedFinancialStatementsOfUnitedCommunityBanksIncParentOnlyTables 138 false false R139.htm 2424403 - Disclosure - Condensed Financial Statements of United Community Banks, Inc. (Parent Only) - Balance Sheets (Details) Sheet http://ucbi.com/role/CondensedFinancialStatementsOfUnitedCommunityBanksIncParentOnlyBalanceSheetsDetails Condensed Financial Statements of United Community Banks, Inc. (Parent Only) - Balance Sheets (Details) Details http://ucbi.com/role/CondensedFinancialStatementsOfUnitedCommunityBanksIncParentOnlyTables 139 false false R140.htm 2424404 - Disclosure - Condensed Financial Statements of United Community Banks, Inc. (Parent Only) - Statements of Cash Flows (Details) Sheet http://ucbi.com/role/CondensedFinancialStatementsOfUnitedCommunityBanksIncParentOnlyStatementsOfCashFlowsDetails Condensed Financial Statements of United Community Banks, Inc. (Parent Only) - Statements of Cash Flows (Details) Details http://ucbi.com/role/CondensedFinancialStatementsOfUnitedCommunityBanksIncParentOnlyTables 140 false false R141.htm 2425401 - Disclosure - Subsequent Events - Narrative (Details) Sheet http://ucbi.com/role/SubsequentEventsNarrativeDetails Subsequent Events - Narrative (Details) Details 141 false false R9999.htm Uncategorized Items - ucbi-20181231.xml Sheet http://xbrl.sec.gov/role/uncategorizedFacts Uncategorized Items - ucbi-20181231.xml Cover 142 false false All Reports Book All Reports ucbi-20181231.xml ucbi-20181231.xsd ucbi-20181231_cal.xml ucbi-20181231_def.xml ucbi-20181231_lab.xml ucbi-20181231_pre.xml http://xbrl.sec.gov/dei/2014-01-31 http://fasb.org/us-gaap/2017-01-31 true true