Regulatory Matters (Details) $ in Thousands	Mar. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
CET1 capital, Minimum	0.045
CET1 capital, Well-Capitalized	0.065
CET1 capital	0.1239	0.1216
Tier 1 capital, Minimum	0.060
Tier 1 capital, Well-Capitalized	0.080
Tier 1 capital	0.1283	0.1260
Total capital, Minimum	0.080
Total capital, Well-Capitalized	0.100
Total capital	0.1464	0.1449
Leverage ratio, Minimum	0.040
Leverage ratio, Well-Capitalized	0.050
Leverage ratio	0.0969	0.0947
CET1 capital	$ 2,468,825	$ 2,432,518
Tier 1 capital	2,557,091	2,520,784
Total capital	2,917,664	2,898,474
Risk-weighted assets	19,933,869	20,007,236
Average total assets for the leverage ratio	$ 26,400,773	$ 26,621,561
United Community Bank
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
CET1 capital	0.1260	0.1222
Tier 1 capital	0.1260	0.1222
Total capital	0.1363	0.1323
Leverage ratio	0.0950	0.0917
CET1 capital	$ 2,502,765	$ 2,435,962
Tier 1 capital	2,502,765	2,435,962
Total capital	2,707,793	2,638,009
Risk-weighted assets	19,861,459	19,933,429
Average total assets for the leverage ratio	$ 26,351,912	$ 26,563,946