FAIR VALUE - CARRYING AMOUNTS AND FV OF FINANCIAL INSTRUMENTS (Details) - USD ($)
$ in Thousands
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Assets:        
Securities available for sale $ 481,275 $ 517,058    
Securities to be held to maturity 53,249 39,196    
Aggregate fair value of mortgage loan 11,662 4,083 $ 6,388 $ 3,506
Aggregate fair value of consumer loan 2,198      
Consumer loans held for sale, at the lower of cost or fair value 1,310 514    
Carrying Value        
Assets:        
Cash and cash equivalents 289,309 210,082    
Securities available for sale 481,275 517,058    
Securities to be held to maturity 52,864 38,727    
Aggregate fair value of mortgage loan 11,662 4,083    
Aggregate fair value of consumer loan 2,198      
Consumer loans held for sale, at the lower of cost or fair value 1,310 514    
Loans, net 3,777,858 3,299,119    
Federal Home Loan Bank stock 28,208 28,208    
Accrued interest receivable 10,356 9,233    
Liabilities:        
Securities sold under agreements to repurchase and other short-term borrowings 173,473 395,433    
Federal Home Loan Bank advances 802,500 699,500    
Subordinated note 41,240 41,240    
Accrued interest payable 948 1,229    
Carrying Value | Non Interest Bearing Deposits        
Liabilities:        
Deposit liabilities, fair value 971,937 634,863    
Carrying Value | Transaction deposits        
Liabilities:        
Deposit liabilities, fair value 1,939,338 1,601,647    
Carrying Value | Time deposits.        
Liabilities:        
Deposit liabilities, fair value 249,417 250,967    
Total Fair Value        
Assets:        
Cash and cash equivalents 289,309 210,082    
Securities available for sale 481,275 517,058    
Securities to be held to maturity 53,249 39,196    
Aggregate fair value of mortgage loan 11,662 4,083    
Aggregate fair value of consumer loan 2,198      
Consumer loans held for sale, at the lower of cost or fair value 1,310 514    
Loans, net 3,757,698 3,332,608    
Accrued interest receivable 10,356 9,233    
Liabilities:        
Securities sold under agreements to repurchase and other short-term borrowings 173,473 395,433    
Federal Home Loan Bank advances 798,594 708,722    
Subordinated note 30,821 33,358    
Accrued interest payable 948 1,229    
Total Fair Value | Non Interest Bearing Deposits        
Liabilities:        
Deposit liabilities, fair value 971,937 634,863    
Total Fair Value | Transaction deposits        
Liabilities:        
Deposit liabilities, fair value 1,939,338 1,601,647    
Total Fair Value | Time deposits.        
Liabilities:        
Deposit liabilities, fair value 248,684 250,882    
Total Fair Value | Fair Value, Inputs, Level 1        
Assets:        
Cash and cash equivalents 289,309 210,082    
Securities available for sale 2,455 1,011    
Total Fair Value | Fair Value, Inputs, Level 2        
Assets:        
Securities available for sale 470,843 507,510    
Securities to be held to maturity 53,249 39,196    
Aggregate fair value of mortgage loan 11,662 4,083    
Consumer loans held for sale, at the lower of cost or fair value 1,310 514    
Accrued interest receivable 10,356 9,233    
Liabilities:        
Securities sold under agreements to repurchase and other short-term borrowings 173,473 395,433    
Federal Home Loan Bank advances 798,594 708,722    
Subordinated note 30,821 33,358    
Accrued interest payable 948 1,229    
Total Fair Value | Fair Value, Inputs, Level 2 | Non Interest Bearing Deposits        
Liabilities:        
Deposit liabilities, fair value 971,937 634,863    
Total Fair Value | Fair Value, Inputs, Level 2 | Transaction deposits        
Liabilities:        
Deposit liabilities, fair value 1,939,338 1,601,647    
Total Fair Value | Fair Value, Inputs, Level 2 | Time deposits.        
Liabilities:        
Deposit liabilities, fair value 248,684 250,882    
Total Fair Value | Fair Value, Inputs, Level 3        
Assets:        
Securities available for sale 7,977 8,537    
Aggregate fair value of consumer loan 2,198      
Loans, net 3,757,698 3,332,608    
Recurring basis        
Assets:        
Securities available for sale 481,275 517,058    
Aggregate fair value of mortgage loan 11,662 4,083    
Aggregate fair value of consumer loan 2,198      
Recurring basis | Fair Value, Inputs, Level 1        
Assets:        
Securities available for sale 2,455 1,011    
Recurring basis | Fair Value, Inputs, Level 2        
Assets:        
Securities available for sale 470,843 507,510    
Aggregate fair value of mortgage loan 11,662 4,083    
Recurring basis | Fair Value, Inputs, Level 3        
Assets:        
Securities available for sale 7,977 $ 8,537    
Aggregate fair value of consumer loan $ 2,198