REGULATORY MATTERS (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Tier 1 Leverage ratio [Abstract]
Tier 1 Leverage ratio, actual amount	$ 788,717	$ 705,163
Tier 1 Leverage ratio, actual ratio	10.32%	9.96%
Tier 1 leverage ratio for capital adequacy purposes, amount	$ 305,761	$ 283,255
Tier 1 leverage ratio for capital adequacy purposes, ratio	4.00%	4.00%
Tier 1 leverage capital to be well-capitalized under prompt corrective action, amount	$ 382,201	$ 354,069
Tier 1 leverage capital to be well-capitalized under prompt corrective action, ratio	5.00%	5.00%
Tier 1 risk-based capital [Abstract]
Tier 1 risk-based capital, actual amount	$ 788,717	$ 705,163
Tier 1 risk-based capital, actual ratio	17.09%	17.61%
Tier 1 risk-based capital for capital adequacy purposes, amount	$ 276,886	$ 160,214
Tier 1 risk-based capital for capital adequacy purposes, ratio	6.00%	4.00%
Tier 1 risk based capital to be well-capitalized under prompt corrective action, amount	$ 369,181	$ 240,321
Tier 1 risk-based capital to be well-capitalized under prompt corrective action, ratio	8.00%	6.00%
Total risk-based capital [Abstract]
Total risk-based capital, actual amount	$ 834,539	$ 750,942
Total risk-based capital, actual ratio	18.08%	18.75%
Total risk-based capital for capital adequacy purposes, amount	$ 369,181	$ 320,428
Total risk-based capita for capital adequacy purposes, ratio	8.00%	8.00%
Total risk based capital to be well-capitalized under prompt corrective action, amount	$ 461,477	$ 400,535
Total risk based capital to be well-capitalized under prompt corrective action, ratio	10.00%	10.00%
Common equity Tier 1 capital [Abstract]
Common equity Tier 1 capital, actual amount	$ 689,528
Common equity Tier 1 capital, actual ratio	14.94%
Common equity Tier 1 capital for capital adequacy purposes, amount	$ 207,664
Common equity Tier 1 capital for capital adequacy purposes, ratio	4.50%
Common equity Tier 1 capital to be well-capitalized under prompt corrective action, amount	$ 299,960
Common equity Tier 1 capital to be well-capitalized under prompt corrective action, ratio	6.50%
Community Bank, N.A. [Member]
Tier 1 Leverage ratio [Abstract]
Tier 1 Leverage ratio, actual amount	$ 673,443	$ 584,014
Tier 1 Leverage ratio, actual ratio	8.88%	8.27%
Tier 1 leverage ratio for capital adequacy purposes, amount	$ 303,256	$ 282,517
Tier 1 leverage ratio for capital adequacy purposes, ratio	4.00%	4.00%
Tier 1 leverage capital to be well-capitalized under prompt corrective action, amount	$ 379,070	$ 353,146
Tier 1 leverage capital to be well-capitalized under prompt corrective action, ratio	5.00%	5.00%
Tier 1 risk-based capital [Abstract]
Tier 1 risk-based capital, actual amount	$ 673,443	$ 584,014
Tier 1 risk-based capital, actual ratio	14.65%	14.64%
Tier 1 risk-based capital for capital adequacy purposes, amount	$ 275,739	$ 159,603
Tier 1 risk-based capital for capital adequacy purposes, ratio	6.00%	4.00%
Tier 1 risk based capital to be well-capitalized under prompt corrective action, amount	$ 367,652	$ 239,404
Tier 1 risk-based capital to be well-capitalized under prompt corrective action, ratio	8.00%	6.00%
Total risk-based capital [Abstract]
Total risk-based capital, actual amount	$ 719,265	$ 629,793
Total risk-based capital, actual ratio	15.65%	15.78%
Total risk-based capital for capital adequacy purposes, amount	$ 367,652	$ 319,206
Total risk-based capita for capital adequacy purposes, ratio	8.00%	8.00%
Total risk based capital to be well-capitalized under prompt corrective action, amount	$ 459,565	$ 399,007
Total risk based capital to be well-capitalized under prompt corrective action, ratio	10.00%	10.00%
Common equity Tier 1 capital [Abstract]
Common equity Tier 1 capital, actual amount	$ 673,326
Common equity Tier 1 capital, actual ratio	14.65%
Common equity Tier 1 capital for capital adequacy purposes, amount	$ 206,804
Common equity Tier 1 capital for capital adequacy purposes, ratio	4.50%
Common equity Tier 1 capital to be well-capitalized under prompt corrective action, amount	$ 298,717
Common equity Tier 1 capital to be well-capitalized under prompt corrective action, ratio	6.50%