LOANS (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Jun. 30, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Deferred fees	$ 0		$ 9,143
Allowance for credit losses	232,192	$ 139,073	47,576	$ 45,364
Net loans and leases	9,120,288		8,424,464
Reverse mortgage, fair value	16,100		16,600	15,900
Accrued interest receivable on loans and leases	46,600		31,500
Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	910,971		1,016,500
Allowance for credit losses	9,171	11,593	1,381	1,358
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	1,133,371		1,128,731
Allowance for credit losses	21,317	20,370	7,387	7,994
Financing Receivable Portfolio Segment, Including Reverse Mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	9,352,480		8,481,183
Commercial and industrial | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	2,953,701		2,046,798
Allowance for credit losses	144,225	65,771	22,849	22,004
Owner-occupied commercial | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	1,337,253		1,296,466
Allowance for credit losses	8,956	9,541	4,616	4,480
Commercial mortgages | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	2,165,547		2,222,976
Allowance for credit losses	38,397	26,600	7,452	6,544
Construction | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	638,504		581,082
Allowance for credit losses	10,126	$ 5,198	3,891	$ 2,984
Commercial small business leases | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	213,133		$ 188,630
Paycheck Protection Program, CARES Act | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	$ 945,100