Assets and Liabilities Measured at Fair Value - Narrative (Details)	3 Months Ended
Mar. 31, 2024
Fair Value Disclosures [Abstract]
Maximum remaining maturity of financial instruments having no defined maturity	180 days

Maximum remaining maturity of financial instruments having no defined maturity.

No definition available.

Name:	ucbi_MaximumRemainingMaturityOfFinancialInstrumentsHavingNoDefinedMaturity
Namespace Prefix:	ucbi_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration