LOANS AND LEASES - Commercial and Consumer Credit Exposure by Risk Attribute (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 8,980,786	$ 8,824,214
Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	6,828,038	6,736,493
Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	84,472	63,850
Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	127,462	111,349
Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	0	0
Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	2,547,997	2,514,661
Commercial | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	2,411,763	2,432,834
Commercial | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	62,333	24,594
Commercial | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	73,901	57,233
Commercial | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	0	0
Construction real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	497,683	548,935
Construction real estate | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	497,082	548,323
Construction real estate | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	0	603
Construction real estate | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	601	9
Construction real estate | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	0	0
Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	3,903,654	3,754,681
Commercial real estate | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	3,832,028	3,664,434
Commercial real estate | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	21,507	38,653
Commercial real estate | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	50,119	51,594
Commercial real estate | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	0	0
Lease financing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	90,638	93,415
Lease financing | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	87,165	90,902
Lease financing | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	632	0
Lease financing | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	2,841	2,513
Lease financing | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	0	0
Total commercial loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	7,039,972	6,911,692
Residential real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	1,015,820	955,646
Residential real estate | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	999,843	939,936
Residential real estate | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	15,977	15,710
Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	787,139	817,282
Home equity | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	781,895	811,108
Home equity | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	5,244	6,174
Installment
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	89,149	93,212
Installment | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	88,954	93,038
Installment | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	195	174
Credit card
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	48,706	46,382
Credit card | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	48,599	46,382
Credit card | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	107	0
Total consumer loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	1,940,814	1,912,522
Total consumer loans | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	1,919,291	1,890,464
Total consumer loans | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 21,523	$ 22,058