REGULATORY MATTERS AND CAPITAL (Schedule of Bank Capital and Ratio) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common Equity Tier 1 capital to risk weighted assets, actual amount	$ 737,204	$ 699,728
Common Equity Tier 1 capital to risk weighted assets, actual ratio	9.04%	9.72%
Common Equity Tier 1 capital to risk weighted assets, required for capital adequacy purposes, amount	$ 367,073	$ 324,035
Common Equity Tier 1 capital to risk weighted assets, required for capital adequacy purposes, ratio	4.50%	4.50%
Tier 1 capital to risk weighted assets, actual amount	$ 826,979	$ 790,228
Tier 1 capital to risk weighted assets, actual ratio	10.14%	10.97%
Tier 1 capital to risk weighted assets, required for capital adequacy purposes, amount	$ 489,428	$ 432,047
Tier 1 capital ratio of risk-weighted assets	6.00%	6.00%
Total capital to risk weighted assets, actual amount	$ 1,013,788	$ 976,145
Total capital to risk weighted assets, actual ratio	12.43%	13.56%
Total capital to risk weighted assets, Required for Capital adequacy purposes, amount	$ 652,573	$ 576,062
Total capital to risk weighted assets, required for capital adequacy purposes, ratio	8.00%	8.00%
Tier 1 capital to average adjusted assets, actual amount	$ 826,979	$ 790,228
Tier 1 capital to average adjusted assets, actual ratio	9.42%	9.87%
Tier 1 capital to average adjusted assets, required for capital adequacy purposes, amount	$ 351,230	$ 320,316
Tier 1 capital to average adjusted assets, required for capital adequacy purposes, ratio	4.00%	4.00%
Union Bank & Trust
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common Equity Tier 1 capital to risk weighted assets, actual amount	$ 947,432	$ 901,783
Common Equity Tier 1 capital to risk weighted assets, actual ratio	11.66%	12.58%
Common Equity Tier 1 capital to risk weighted assets, required for capital adequacy purposes, amount	$ 365,616	$ 322,531
Common Equity Tier 1 capital to risk weighted assets, required for capital adequacy purposes, ratio	4.50%	4.50%
Common Equity Tier 1 capital to risk weighted assets, required in order to be well capitalized under PCA, amount	$ 528,111	$ 465,878
Common Equity Tier 1 capital to risk weighted assets, required in order to be well capitalized under PCA, ratio	6.50%	6.50%
Tier 1 capital to risk weighted assets, actual amount	$ 947,432	$ 901,783
Tier 1 capital to risk weighted assets, actual ratio	11.66%	12.58%
Tier 1 capital to risk weighted assets, required for capital adequacy purposes, amount	$ 487,488	$ 430,042
Tier 1 capital ratio of risk-weighted assets	6.00%	6.00%
Tier 1 capital to risk weighted assets, required in order to be well capitalized under PCA, amount	$ 649,983	$ 573,389
Tier 1 capital to risk weighted assets, required in order to be well capitalized under PCA, ratio	8.00%	8.00%
Total capital to risk weighted assets, actual amount	$ 986,040	$ 939,700
Total capital to risk weighted assets, actual ratio	12.14%	13.11%
Total capital to risk weighted assets, Required for Capital adequacy purposes, amount	$ 649,983	$ 573,390
Total capital to risk weighted assets, required for capital adequacy purposes, ratio	8.00%	8.00%
Total capital to risk weighted assets, required in order to be well capitalized under PCA, amount	$ 812,478	$ 716,737
Total capital to risk weighted assets, required in order to be well capitalized under PCA, ratio	10.00%	10.00%
Tier 1 capital to average adjusted assets, actual amount	$ 947,432	$ 901,783
Tier 1 capital to average adjusted assets, actual ratio	10.82%	11.31%
Tier 1 capital to average adjusted assets, required for capital adequacy purposes, amount	$ 350,126	$ 319,046
Tier 1 capital to average adjusted assets, required for capital adequacy purposes, ratio	4.00%	4.00%
Tier 1 capital to average adjusted assets, required in order to be well capitalized under PCA, amount	$ 437,657	$ 398,807
Tier 1 capital to average adjusted assets, required in order to be well capitalized under PCA, ratio	5.00%	5.00%