DEPOSITS AND RETAIL REPURCHASE AGREEMENTS (Deposit Liabilities) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Deposits:
Non-interest-bearing accounts	$ 1,484,315	$ 1,298,866
Interest-bearing checking	477,492	439,480
Regular savings accounts	1,003,189	901,142
Money market accounts	566,369	488,946
Total transaction and saving accounts	3,531,365	3,128,434
Certificates of deposit	765,780	770,516
Total deposits	$ 4,297,145	$ 3,898,950
Non-interest-bearing accounts, percent of total	34.50%	33.30%
Interest-bearing checking, percent of total	11.10%	11.30%
Regular savings accounts, percent of total	23.40%	23.10%
Money market accounts, percent of total	13.20%	12.50%
Total transaction and saving accounts, percent of total	82.20%	80.20%
Certificates of deposit, percent of total	17.80%	19.80%
Total deposits, percent of total	100.00%	100.00%
Included in total deposits:
Public fund transaction accounts	$ 116,030	$ 102,854
Public fund interest-bearing certificates	33,577	35,346
Total public deposits	149,607	138,200
Total brokered deposits	$ 9,646	$ 4,799
Public fund transaction accounts, percent of total	2.70%	2.60%
Public fund interest-bearing certificates, percent of total	0.80%	0.90%
Total public deposits, percent of total	3.50%	3.50%
Total brokered deposits, percent of total	0.20%	0.10%