LOANS (Loan Portfolio Segment Balances) (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 10,446,866	$ 10,400,509
Commercial investor real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	3,652,418	3,634,720
Commercial owner-occupied real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	1,644,848	1,642,216
Commercial AD&C
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	1,051,013	1,050,973
Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	1,022,546	1,105,179
Residential construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	171,028	182,619
Commercial real estate: | Commercial investor real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	3,652,418	3,634,720
Commercial real estate: | Commercial owner-occupied real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	1,644,848	1,642,216
Commercial real estate: | Commercial AD&C
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	1,051,013	1,050,973
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	8,759,388	8,595,457
Commercial | Commercial business
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	2,411,109	2,267,548
Residential real estate: | Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	1,022,546	1,105,179
Residential real estate: | Residential construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	171,028	182,619
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	493,904	517,254
Total residential and consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 1,687,478	$ 1,805,052