LOANS - Narrative (Detail) - USD ($) $ in Thousands		9 Months Ended
	Apr. 01, 2020	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Loans and Leases Receivable Disclosure [Line Items]
Net deferred loan fees		$ 28,300		$ 1,800
Loans receivable with a gross amortized cost basis	$ 2,500,000
PCD Loans acquired	974,800
Initial allowance on acquired Revere PCD loans	18,600	18,628	$ 0
Fair value premium	4,500
Total fair value of PCD loans as of the Acquisition Date	960,700	901,900
PCD remaining unamortized fair value premium		4,000
PCD loans non-accruing at the time of acquisition	11,300
Non-PCD loans	1,500,000	1,400,000
Net fair value premium	$ 2,100
Non-PCD remaining unamortized fair value premium		1,500
Paycheck Protection Program
Loans and Leases Receivable Disclosure [Line Items]
Net deferred loan fees		$ 25,500