LOANS AND LEASES - Additional Information (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2020 USD ($) loans	Sep. 30, 2019 USD ($) loans	Sep. 30, 2020 USD ($) loans	Sep. 30, 2019 USD ($) loans	Jun. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)	Jun. 30, 2019 USD ($)	Dec. 31, 2018 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Modifications, Number of Contracts	7	11	39	53
Financing Receivable, Troubled Debt Restructuring, Subsequent Default		$ 100,000		$ 7,000,000.0
Financing Receivable, Troubled Debt Restructuring, Subsequent Default, Number of Contracts | loans	1	1	1	3
Restructured Loans, Portion Determined to be Uncollectible	$ 600,000	$ 2,300,000	$ 1,700,000	$ 2,300,000
Purchased impaired loans						$ 68,664,000
Restructured Loans, Nonaccrual Status	29,300,000		29,300,000			18,500,000
Real Estate Acquired Through Foreclosure	1,643,000	$ 1,613,000	1,643,000	$ 1,613,000	$ 1,872,000	2,033,000	$ 1,421,000	$ 1,401,000
Troubled Debt Restructuring	37,100,000		37,100,000			30,000,000.0
Loans and Leases Receivable, Net Amount	10,032,265,000		10,032,265,000			9,144,015,000
Financing Receivable, Non-Troubled Debt Restructuring Modifications, Amount	$ 1,500,000,000		$ 1,500,000,000
Total consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	0	1	1	1
Commercial segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	1	2	8	8
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Restructured Loans, Loan Relationships, Review Threshold Amount Minimum			$ 250,000
Residential real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	2	5	20	22
Restructured Loans, Loan Relationships, Review Threshold Amount Minimum			$ 250,000
Commercial segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchased impaired loans						$ 3,081,000
Paycheck Protection Program Amount Of Funding	$ 886,100,000		886,100,000
Unearned fees	24,200,000		24,200,000
Payment Deferral [Member] | Loan Deferrals Second Round [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Non-Troubled Debt Restructuring Modifications, Amount	631,200,000		631,200,000
Payment Deferral [Member] | Loan Deferrals Second Round [Member] | Hotel [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Non-Troubled Debt Restructuring Modifications, Amount	438,200,000		$ 438,200,000
Financing Receivable, Non-Troubled Debt Restructuring Modifications, Percent			69.00%
Payment Deferral [Member] | Total consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Non-Troubled Debt Restructuring Modifications, Amount	131,400,000		$ 131,400,000
Financing Receivable, Non-Troubled Debt Restructuring Modifications, Number of Contracts | loans			1,830
Payment Deferral [Member] | Commercial segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Non-Troubled Debt Restructuring Modifications, Amount	$ 2,100,000,000		$ 2,100,000,000
Financing Receivable, Non-Troubled Debt Restructuring Modifications, Number of Contracts | loans			1,902