BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES - Risk and Uncertainties Related to COVID19 (Detail) $ in Thousands		3 Months Ended
	May 07, 2020 USD ($) numberofcontracts	Mar. 31, 2020 USD ($) numberofcontracts	Mar. 31, 2019 USD ($)	Dec. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase (decrease) in ACL		$ 137,700
Provision for credit losses		77,366	$ 11,408
Net charge-offs		17,600
Loans and Leases Receivable, Gross		9,000
Available unused lines at the FHLB	$ 383,700	$ 529,400
FED Discount Window funds availability	973,200
Excess Cash And Liquid Securities Total Assets Ratio		17.50%		15.80%
COVID-19
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase (decrease) in ACL		$ 59,800
COVID-19 | Small Business Administration
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
SBA PPP number of applications | numberofcontracts		3,792
SBA loans approved	350,600
SBA loans funded	$ 313,200
COVID-19 | Payment Deferral [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Loan Deferral Program Description		In working with borrowers affected by the COVID-19 pandemic, the Corporation implemented payment deferral programs to alleviate the hardships being experienced by the Corporation’s borrowers. The payment deferral programs, which the Corporation implemented in March 2020, provided deferred repayment arrangements across-the-board up to June 30, 2019 to consumer borrowers (i.e., residential mortgage, personal loans, auto loans, finance leases, small loans, and credit cards) who qualify for the program based, among other things, on the delinquency status of the loan on March 16, 2019, and who did not make their payment corresponding to the month of March, with the possibility of extension up to August 31, 2020, if needed. For commercial loans, any request for payment deferral is analyzed on a case by case basis.
COVID-19 | Residential Portfolio Segment [Member] | Payment Deferral [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred repayment arrangements | numberofcontracts	7,064
Loans and Leases Receivable, Gross	$ 931,500
COVID-19 | Commercial Portfolio Segment [Member] | Accomodation, Retail Real Estate And Transportation Industries [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Percentage of Loan Expsoure to Industries		28.00%
COVID-19 | Commercial Portfolio Segment [Member] | Payment Deferral [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred repayment arrangements | numberofcontracts	741
Loans and Leases Receivable, Gross	$ 1,800,000
COVID-19 | Consumer Portfolio Segment [Member] | Payment Deferral [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred repayment arrangements | numberofcontracts	93,629
Loans and Leases Receivable, Gross	$ 1,000,000