Regulatory Matters - Regulatory capital ratios and minimum amounts required (Details) $ in Thousands	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Risk-based ratios:
CET1 capital, Minimum	0.045
CET1 capital, Well Capitalized	0.065
CET1 capital	0.1246	0.1231
Tier 1 capital, Minimum	0.060
Tier 1 capital, Well Capitalized	0.080
Tier 1 capital	0.1317	0.1310
Total capital, Minimum	0.080
Total capital, Well Capitalized	0.100
Total capital	0.1465	0.1515
Tier 1 leverage ratio, Minimum	0.040
Tier 1 leverage ratio, Well Capitalized	0.050
Tier 1 leverage ratio	0.0875	0.0928
CET1 capital	$ 1,688,176	$ 1,506,750
Tier 1 capital	1,784,598	1,603,172
Total capital	1,984,376	1,854,368
RWAs	13,548,534	12,240,440
Average total assets	$ 20,402,842	$ 17,276,853
United Community Bank
Risk-based ratios:
CET1 capital	0.1287	0.1331
Tier 1 capital	0.1287	0.1331
Total capital	0.1346	0.1428
Tier 1 leverage ratio	0.0853	0.0942
CET1 capital	$ 1,738,557	$ 1,625,292
Tier 1 capital	1,738,557	1,625,292
Total capital	1,818,335	1,743,045
RWAs	13,512,405	12,207,940
Average total assets	$ 20,377,319	$ 17,246,878