This element represents debt instrument earliest call year.

No definition available.

Name:	ucbi_DebtInstrumentEarliestCallYear
Namespace Prefix:	ucbi_
Data Type:	xbrli:gYearItemType
Balance Type:	na
Period Type:	duration

- Definition

This element represents debt instrument issue year.

+ References

No definition available.

+ Details

Name:	ucbi_DebtInstrumentIssueYear
Namespace Prefix:	ucbi_
Data Type:	xbrli:gYearItemType
Balance Type:	na
Period Type:	duration

- Definition

This element represents debt instruments maturity year.

+ References

No definition available.

+ Details

Name:	ucbi_DebtInstrumentsMaturityYear
Namespace Prefix:	ucbi_
Data Type:	xbrli:gYearItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

+ References

+ Details

Name:	us-gaap_DebtInstrumentCarryingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

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-SubTopic 20
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+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

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.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, after accumulated amortization, of debt discount.

+ References

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+ Details

Name:	us-gaap_DebtInstrumentUnamortizedDiscount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount, excluding unamortized premium (discount) and debt issuance cost, of long-term debt. Excludes lease obligation.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Name:	us-gaap_LongTermDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_SeniorNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=ucbi_TwoThousandTwentySevenSeniorDebenturesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementScenarioAxis=srt_ScenarioForecastMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=ucbi_TwoThousandThirtySeniorDebenturesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_SecuredOvernightFinancingRateSofrOvernightIndexSwapRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_SubordinatedDebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=ucbi_TwoThousandTwentyEightSubordinatedDebenturesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=ucbi_TwoThousandTwentyNineSubordinatedDebenturesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=ucbi_TrustPreferredSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=ucbi_TidelandsStatutoryTrustOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=ucbi_FourOaksStatutoryTrustIMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=ucbi_CommunityFirstCapitalTrustOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_PrimeRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=ucbi_CommunityFirstCapitalTrustTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=ucbi_CommunityFirstCapitalTrustThreeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Long-term Debt - Schedule of long-term debt (Details) - USD ($) $ in Thousands	12 Months Ended	28 Months Ended	60 Months Ended	66 Months Ended	71 Months Ended
	Dec. 31, 2022	Dec. 31, 2027	Dec. 31, 2029	Dec. 31, 2030	Dec. 31, 2028	Dec. 31, 2021
Debt Instrument [Line Items]
Less net discount	$ (4,669)					$ (8,260)
Total long-term debt	324,663					247,360
Senior debentures
Debt Instrument [Line Items]
Long-term debt, gross	135,000					135,000
Senior debentures \| 2027 senior debentures
Debt Instrument [Line Items]
Long-term debt, gross	$ 35,000					35,000
Issue Date	2015
Stated Maturity Date	2027
Earliest Call Date	2025
Interest Rate (percent)	5.50%
Senior debentures \| 2027 senior debentures \| LIBOR \| Forecast
Debt Instrument [Line Items]
Basis spread on variable rate (percent)		3.71%
Senior debentures \| 2030 senior debentures
Debt Instrument [Line Items]
Long-term debt, gross	$ 100,000					100,000
Issue Date	2020
Stated Maturity Date	2030
Earliest Call Date	2025
Interest Rate (percent)	5.00%
Senior debentures \| 2030 senior debentures \| SOFR \| Forecast
Debt Instrument [Line Items]
Basis spread on variable rate (percent)				4.87%
Subordinated debentures
Debt Instrument [Line Items]
Long-term debt, gross	$ 160,000					100,000
Subordinated debentures \| 2028 subordinated debentures
Debt Instrument [Line Items]
Long-term debt, gross	$ 100,000					100,000
Issue Date	2018
Stated Maturity Date	2028
Earliest Call Date	2023
Interest Rate (percent)	4.50%
Subordinated debentures \| 2028 subordinated debentures \| LIBOR \| Forecast
Debt Instrument [Line Items]
Basis spread on variable rate (percent)					2.12%
Subordinated debentures \| 2029 subordinated debentures
Debt Instrument [Line Items]
Long-term debt, gross	$ 60,000					0
Issue Date	2019
Stated Maturity Date	2029
Earliest Call Date	2024
Interest Rate (percent)	5.125%
Subordinated debentures \| 2029 subordinated debentures \| SOFR \| Forecast
Debt Instrument [Line Items]
Basis spread on variable rate (percent)			3.765%
Trust preferred securities
Debt Instrument [Line Items]
Long-term debt, gross	$ 34,332					20,620
Trust preferred securities \| Tidelands Statutory Trust I
Debt Instrument [Line Items]
Long-term debt, gross	$ 8,248					8,248
Issue Date	2006
Stated Maturity Date	2036
Trust preferred securities \| Tidelands Statutory Trust I \| LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate (percent)	1.38%
Trust preferred securities \| Four Oaks Statutory Trust I
Debt Instrument [Line Items]
Long-term debt, gross	$ 12,372					12,372
Issue Date	2006
Stated Maturity Date	2036
Trust preferred securities \| Four Oaks Statutory Trust I \| LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate (percent)	1.35%
Trust preferred securities \| Community First Capital Trust I
Debt Instrument [Line Items]
Long-term debt, gross	$ 3,093					0
Issue Date	2002
Stated Maturity Date	2032
Trust preferred securities \| Community First Capital Trust I \| Prime Rate
Debt Instrument [Line Items]
Basis spread on variable rate (percent)	0.50%
Trust preferred securities \| Community First Capital Trust II
Debt Instrument [Line Items]
Long-term debt, gross	$ 5,155					0
Issue Date	2005
Stated Maturity Date	2035
Trust preferred securities \| Community First Capital Trust II \| LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate (percent)	1.50%
Trust preferred securities \| Community First Capital Trust III
Debt Instrument [Line Items]
Long-term debt, gross	$ 5,464					$ 0
Issue Date	2007
Stated Maturity Date	2037
Trust preferred securities \| Community First Capital Trust III \| LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate (percent)	3.00%