LOANS (Loan Portfolio Segment Balances) (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 10,333,935	$ 6,705,232
Commercial real estate: | Commercial investor real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	3,588,702	2,169,156
Commercial real estate: | Commercial owner-occupied real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	1,652,208	1,288,677
Commercial real estate: | Commercial AD&C
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	994,800	684,010
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	8,462,956	4,942,862
Commercial | Commercial business
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	2,227,246	801,019
Residential real estate: | Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	1,173,857	1,149,327
Residential real estate: | Residential construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	175,123	146,279
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	521,999	466,764
Total residential and consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 1,870,979	$ 1,762,370