LOANS - Risk category (Details)
$ in Thousands
12 Months Ended
Dec. 31, 2016
USD ($)
region
Dec. 31, 2015
USD ($)
Risk category    
Number of main regions | region 4  
Total loans $ 2,319,976 $ 1,995,589
Commercial loan portfolio    
Risk category    
Total loans 1,604,767 1,526,623
Non-PCI loans    
Risk category    
Total loans 2,291,720 1,957,112
Non-PCI loans | Commercial loan portfolio    
Risk category    
Total loans 1,583,380 1,496,396
Non-PCI loans | Commercial loan portfolio | Acceptable credit quality    
Risk category    
Total loans 1,511,506 1,424,957
Non-PCI loans | Commercial loan portfolio | Special mention    
Risk category    
Total loans 19,665 40,866
Non-PCI loans | Commercial loan portfolio | Substandard    
Risk category    
Total loans 34,277 11,551
Non-PCI loans | Commercial loan portfolio | Substandard - nonaccrual    
Risk category    
Total loans 10,725 14,546
Non-PCI loans | Commercial loan portfolio | Not graded    
Risk category    
Total loans 7,207 4,476
Non-PCI loans | Other loan portfolio    
Risk category    
Total loans 708,340 460,716
Non-PCI loans | Other loan portfolio | Performing    
Risk category    
Total loans 701,767 456,112
Non-PCI loans | Other loan portfolio | Impaired    
Risk category    
Total loans 6,573 4,604
Commercial | Commercial loan portfolio    
Risk category    
Total loans 457,827 499,573
Commercial | Non-PCI loans | Commercial loan portfolio    
Risk category    
Total loans 454,310 493,445
Commercial | Non-PCI loans | Commercial loan portfolio | Acceptable credit quality    
Risk category    
Total loans 426,560 467,355
Commercial | Non-PCI loans | Commercial loan portfolio | Special mention    
Risk category    
Total loans 10,930 16,589
Commercial | Non-PCI loans | Commercial loan portfolio | Substandard    
Risk category    
Total loans 12,649 3,448
Commercial | Non-PCI loans | Commercial loan portfolio | Substandard - nonaccrual    
Risk category    
Total loans 3,559 5,702
Commercial | Non-PCI loans | Commercial loan portfolio | Not graded    
Risk category    
Total loans 612 351
Non residential real estate | Commercial loan portfolio    
Risk category    
Total loans 969,615 876,784
Non residential real estate | Non-PCI loans | Commercial loan portfolio    
Risk category    
Total loans 963,895 862,744
Non residential real estate | Non-PCI loans | Commercial loan portfolio | Acceptable credit quality    
Risk category    
Total loans 925,244 821,314
Non residential real estate | Non-PCI loans | Commercial loan portfolio | Special mention    
Risk category    
Total loans 8,735 23,737
Non residential real estate | Non-PCI loans | Commercial loan portfolio | Substandard    
Risk category    
Total loans 21,178 8,103
Non residential real estate | Non-PCI loans | Commercial loan portfolio | Substandard - nonaccrual    
Risk category    
Total loans 7,145 8,844
Non residential real estate | Non-PCI loans | Commercial loan portfolio | Not graded    
Risk category    
Total loans 1,593 746
Construction and land development | Commercial loan portfolio    
Risk category    
Total loans 177,325 150,266
Construction and land development | Non-PCI loans | Commercial loan portfolio    
Risk category    
Total loans 165,175 140,207
Construction and land development | Non-PCI loans | Commercial loan portfolio | Acceptable credit quality    
Risk category    
Total loans 159,702 136,288
Construction and land development | Non-PCI loans | Commercial loan portfolio | Special mention    
Risk category    
Total loans   540
Construction and land development | Non-PCI loans | Commercial loan portfolio | Substandard    
Risk category    
Total loans 450  
Construction and land development | Non-PCI loans | Commercial loan portfolio | Substandard - nonaccrual    
Risk category    
Total loans 21  
Construction and land development | Non-PCI loans | Commercial loan portfolio | Not graded    
Risk category    
Total loans 5,002 3,379
Residential real estate | Other loan portfolio    
Risk category    
Total loans 253,713 163,224
Residential real estate | Non-PCI loans | Other loan portfolio    
Risk category    
Total loans 247,156 155,266
Residential real estate | Non-PCI loans | Other loan portfolio | Performing    
Risk category    
Total loans 242,127 151,111
Residential real estate | Non-PCI loans | Other loan portfolio | Impaired    
Risk category    
Total loans 5,029 4,155
Consumer | Other loan portfolio    
Risk category    
Total loans 270,017 161,512
Consumer | Non-PCI loans | Other loan portfolio    
Risk category    
Total loans 269,705 161,220
Consumer | Non-PCI loans | Other loan portfolio | Performing    
Risk category    
Total loans 269,492 161,169
Consumer | Non-PCI loans | Other loan portfolio | Impaired    
Risk category    
Total loans 213 51
Lease financing | Other loan portfolio    
Risk category    
Total loans 191,479 144,230
Lease financing | Non-PCI loans | Other loan portfolio    
Risk category    
Total loans 191,479 144,230
Lease financing | Non-PCI loans | Other loan portfolio | Performing    
Risk category    
Total loans 190,148 143,832
Lease financing | Non-PCI loans | Other loan portfolio | Impaired    
Risk category    
Total loans $ 1,331 $ 398