BUSINESS COMBINATIONS - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Mar. 31, 2016	Mar. 11, 2016	Oct. 14, 2015	Jul. 17, 2015
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets			$ 417,000,000
Goodwill	$ 25,211,000	$ 55,196,000
The Bank shares Inc [Member]
Business Acquisition [Line Items]
Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Noncurrent Liabilities Deposits					$ 188,400,000
Business Combination Recognized Identifiable Assets Acquired and Liabilities Assumed Noncurrent Assets Loans					$ 111,300,000
Business Combination, Bargain Purchase, Gain Recognized, Amount	416,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill, Total	$ 2,600,000
Floridian Financial Group [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets			12,879,000
Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Noncurrent Liabilities Deposits			337,000,000
Business Combination Recognized Identifiable Assets Acquired and Liabilities Assumed Noncurrent Assets Loans			$ 268,000,000
Business Acquisition, Percentage of Voting Interests Acquired			100.00%
Goodwill			$ 29,985,000
BMO Harris Central [Member]
Business Acquisition [Line Items]
Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Noncurrent Liabilities Deposits				$ 355,000,000
Business Combination Recognized Identifiable Assets Acquired and Liabilities Assumed Noncurrent Assets Loans				$ 70,000,000
Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Deposit Premium Percentage				3.00%