Regulatory Matters - Regulatory capital ratios and minimum amounts required (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Risk-based ratios:
Common equity tier 1 capital, Minimum	4.50%
Common equity tier 1 capital, Well Capitalized	6.50%
Common equity tier 1 capital	12.16%	11.98%
Tier 1 capital, Minimum	6.00%
Tier 1 capital, Well Capitalized	8.00%
Tier 1 capital	12.42%	12.24%
Total capital, Minimum	8.00%
Total capital, Well Capitalized	10.00%
Total capital	14.29%	13.06%
Tier 1 Leverage ratio, Minimum	4.00%
Tier 1 Leverage Ratio, Well Capitalized	5.00%
Tier 1 Leverage ratio	9.61%	9.44%
Common equity tier 1 capital	$ 1,148,355	$ 1,053,983
Tier 1 capital	1,172,605	1,076,465
Total capital	1,348,843	1,149,191
Risk-weighted assets	9,441,622	8,797,387
Average total assets	$ 12,207,986	$ 11,403,248
United Community Bank
Risk-based ratios:
Common equity tier 1 capital	12.91%	12.93%
Tier 1 capital	12.91%	12.93%
Total capital	13.60%	13.63%
Tier 1 Leverage ratio	9.98%	9.98%
Common equity tier 1 capital	$ 1,216,449	$ 1,135,728
Tier 1 capital	1,216,449	1,135,728
Total capital	1,281,062	1,196,954
Risk-weighted assets	9,421,009	8,781,177
Average total assets	$ 12,183,341	$ 11,385,716

Common Equity Tier 1 Capital Required To Be Well Capitalized To Risk Weighted Assets.

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Common Equity Tier One Capital Required For Capital Adequacy To Risk Weighted Assets.

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The amount of total capital as defined in the regulations.

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The minimum Total risk based capital ratio (total capital divided by risk weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action.

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The Total risk based capital ratio (total capital divided by risk weighted assets) required to be categorized as "well capitalized", in the regulatory framework for prompt corrective action.

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Total Capital divided by risk weighted assets as defined in the regulations.

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Amount of Common Equity Tier One Risk-based Capital, as defined by regulatory framework.

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Percentage of Common Equity Tier One Risk-based Capital to total risk-weighted assets, as defined by regulatory framework.

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The amount for the individual regulatory asset as itemized in a table of regulatory assets as of the end of the period.

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Amount of risk-weighted assets as calculated in accordance with U.S. Federal regulatory capital standards.

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The minimum amount of Tier 1 Leverage Capital for capital adequacy purposes divided by average assets as defined in the regulations.

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The amount of Tier 1 Leverage Capital required to be categorized as well capitalized divided by average assets as defined in the regulatory framework for prompt corrective action.

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Tier 1 Leverage Capital divided by average assets as defined in the regulations.

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Tier 1 Risk Based Capital as defined in the regulations.

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The minimum Tier One Capital Ratio (Tier one capital divided by risk-weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action.

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The Tier 1 capital ratio (Tier 1 capital divided by risk weighted assets) required to be categorized as "well capitalized" under the regulatory framework for prompt corrective action.

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Tier 1 capital divided by risk weighted assets as defined by regulations.

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