ALLOWANCE FOR LOAN AND LEASE LOSSES - Changes in the Allowance for Loan and Lease Losses (Details) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Sep. 30, 2016
Sep. 30, 2015
Sep. 30, 2016
Sep. 30, 2015
Sep. 30, 2016
Dec. 31, 2015
Allowance for loan and lease losses:            
Balance at beginning of period $ 56,708 $ 52,876 $ 53,398 $ 52,858    
Provision for loan and lease losses 1,687 2,647 7,379 7,777    
Loans charged-off (2,550) (3,962) (7,694) (14,278)    
Recoveries 1,773 1,771 4,535 6,975    
Total net charge-offs (777) (2,191) (3,159) (7,303)    
Balance at end of period 57,618 53,332 57,618 53,332    
Ending allowance on loans individually evaluated for impairment         $ 1,977 $ 1,573
Ending allowance on loans collectively evaluated for impairment         55,641 51,825
Ending allowance for loan and lease losses 56,708 52,876 53,398 52,858 57,618 53,398
Loans and Leases:            
Ending balance of loans individually evaluated for impairment         50,465 56,873
Ending balance of loans collectively evaluated for impairment         5,739,046 5,331,887
Loans and Leases Receivable, Net of Deferred Income         5,789,511 5,388,760
Non Covered Loans            
Allowance for loan and lease losses:            
Balance at beginning of period       52,858    
Ending allowance for loan and lease losses       52,858    
Commercial            
Allowance for loan and lease losses:            
Balance at beginning of period 20,897 16,775 16,995 13,870    
Provision for loan and lease losses (720) 1,303 3,284 4,522    
Loans charged-off (296) (1,808) (1,040) (4,631)    
Recoveries 327 374 969 2,883    
Total net charge-offs 31 (1,434) (71) (1,748)    
Balance at end of period 20,208 16,644 20,208 16,644    
Ending allowance on loans individually evaluated for impairment         777 357
Ending allowance on loans collectively evaluated for impairment         19,431 16,638
Ending allowance for loan and lease losses 20,897 16,775 16,995 13,870 20,208 16,995
Loans and Leases:            
Ending balance of loans individually evaluated for impairment         14,799 17,411
Ending balance of loans collectively evaluated for impairment         1,767,983 1,645,691
Loans and Leases Receivable, Net of Deferred Income         1,782,782 1,663,102
Real estate - construction            
Allowance for loan and lease losses:            
Balance at beginning of period 2,893 1,385 1,810 1,045    
Provision for loan and lease losses 232 153 1,118 431    
Loans charged-off (64) (85) (95) (85)    
Recoveries 6 87 234 149    
Total net charge-offs (58) 2 139 64    
Balance at end of period 3,067 1,540 3,067 1,540    
Ending allowance on loans individually evaluated for impairment         0 0
Ending allowance on loans collectively evaluated for impairment         3,067 1,810
Ending allowance for loan and lease losses 2,893 1,385 1,810 1,045 3,067 1,810
Loans and Leases:            
Ending balance of loans individually evaluated for impairment         0 0
Ending balance of loans collectively evaluated for impairment         380,349 311,712
Loans and Leases Receivable, Net of Deferred Income         380,349 311,712
Real estate - commercial            
Allowance for loan and lease losses:            
Balance at beginning of period 22,784 24,357 23,656 27,086    
Provision for loan and lease losses 2,628 (339) 3,491 (78)    
Loans charged-off (1,135) (1,082) (3,993) (5,668)    
Recoveries 997 691 2,120 2,287    
Total net charge-offs (138) (391) (1,873) (3,381)    
Balance at end of period 25,274 23,627 25,274 23,627    
Ending allowance on loans individually evaluated for impairment         1,019 979
Ending allowance on loans collectively evaluated for impairment         24,255 22,677
Ending allowance for loan and lease losses 22,784 24,357 23,656 27,086 25,274 23,656
Loans and Leases:            
Ending balance of loans individually evaluated for impairment         21,196 24,652
Ending balance of loans collectively evaluated for impairment         2,446,887 2,233,645
Loans and Leases Receivable, Net of Deferred Income         2,468,083 2,258,297
Residential - real estate            
Allowance for loan and lease losses:            
Balance at beginning of period 3,292 3,214 4,014 3,753    
Provision for loan and lease losses (13) 1,224 (806) 1,739    
Loans charged-off (90) (288) (163) (1,449)    
Recoveries 38 237 182 344    
Total net charge-offs (52) (51) 19 (1,105)    
Balance at end of period 3,227 4,387 3,227 4,387    
Ending allowance on loans individually evaluated for impairment         179 235
Ending allowance on loans collectively evaluated for impairment         3,048 3,779
Ending allowance for loan and lease losses 3,292 3,214 4,014 3,753 3,227 4,014
Loans and Leases:            
Ending balance of loans individually evaluated for impairment         9,285 8,994
Ending balance of loans collectively evaluated for impairment         498,430 503,317
Loans and Leases Receivable, Net of Deferred Income         507,715 512,311
Home equity            
Allowance for loan and lease losses:            
Balance at beginning of period 3,002 4,386 3,943 4,260    
Provision for loan and lease losses 275 (724) (247) (269)    
Loans charged-off (475) (268) (1,213) (1,258)    
Recoveries 257 236 576 897    
Total net charge-offs (218) (32) (637) (361)    
Balance at end of period 3,059 3,630 3,059 3,630    
Ending allowance on loans individually evaluated for impairment         2 2
Ending allowance on loans collectively evaluated for impairment         3,057 3,941
Ending allowance for loan and lease losses 3,002 4,386 3,943 4,260 3,059 3,943
Loans and Leases:            
Ending balance of loans individually evaluated for impairment         4,587 5,441
Ending balance of loans collectively evaluated for impairment         459,115 461,188
Loans and Leases Receivable, Net of Deferred Income         463,702 466,629
Installment            
Allowance for loan and lease losses:            
Balance at beginning of period 383 387 386 407    
Provision for loan and lease losses 168 864 107 916    
Loans charged-off (223) (155) (326) (380)    
Recoveries 56 94 217 247    
Total net charge-offs (167) (61) (109) (133)    
Balance at end of period 384 1,190 384 1,190    
Ending allowance on loans individually evaluated for impairment         0 0
Ending allowance on loans collectively evaluated for impairment         384 386
Ending allowance for loan and lease losses 383 387 386 407 384 386
Loans and Leases:            
Ending balance of loans individually evaluated for impairment         384 253
Ending balance of loans collectively evaluated for impairment         47,441 41,253
Loans and Leases Receivable, Net of Deferred Income         47,825 41,506
All other            
Allowance for loan and lease losses:            
Balance at beginning of period 3,457 2,372 2,594 2,437    
Provision for loan and lease losses (883) 166 432 516    
Loans charged-off (267) (276) (864) (807)    
Recoveries 92 52 237 168    
Total net charge-offs (175) (224) (627) (639)    
Balance at end of period 2,399 2,314 2,399 2,314    
Ending allowance on loans individually evaluated for impairment         0 0
Ending allowance on loans collectively evaluated for impairment         2,399 2,594
Ending allowance for loan and lease losses $ 3,457 $ 2,372 $ 2,594 $ 2,437 2,399 2,594
Loans and Leases:            
Ending balance of loans individually evaluated for impairment         214 122
Ending balance of loans collectively evaluated for impairment         138,841 135,081
Loans and Leases Receivable, Net of Deferred Income         $ 139,055 $ 135,203