GOODWILL AND OTHER INTANGIBLES - Gross Amount and Accumulated Amortization of Other Intangible Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets, Gross [Abstract]
Beginning balance	$ 77,196	$ 77,196	$ 77,196
Ending balance	116,428	77,196	77,196
Accumulated amortization:
Beginning balance	(69,623)	(66,537)	(62,944)
Amortization	(5,912)	(3,086)	(3,593)
Ending balance	(75,535)	(69,623)	(66,537)
Net intangible assets	40,893	7,573	10,659
BSPR
Finite-Lived Intangible Assets, Gross [Abstract]
Additions due to acquisitions	39,232
Core Deposits [Member]
Finite-Lived Intangible Assets, Gross [Abstract]
Beginning balance	51,664	51,664	51,664
Ending balance	87,096	51,664	51,664
Accumulated amortization:
Beginning balance	(48,176)	(47,329)	(46,187)
Amortization	(3,078)	(847)	(1,142)
Ending balance	(51,254)	(48,176)	(47,329)
Net intangible assets	35,842	3,488	4,335
Core Deposits [Member] | BSPR
Finite-Lived Intangible Assets, Gross [Abstract]
Additions due to acquisitions	35,432
Customer Relationships [Member] | Credit Card [Member]
Finite-Lived Intangible Assets, Gross [Abstract]
Beginning balance	24,465	24,465	24,465
Ending balance	28,265	24,465	24,465
Accumulated amortization:
Beginning balance	(20,850)	(18,763)	(16,464)
Amortization	(2,682)	(2,087)	(2,299)
Ending balance	(23,532)	(20,850)	(18,763)
Net intangible assets	4,733	3,615	5,702
Customer Relationships [Member] | Credit Card [Member] | BSPR
Finite-Lived Intangible Assets, Gross [Abstract]
Additions due to acquisitions	3,800
Accumulated amortization:
Net intangible assets	3,000
Customer Relationships [Member] | Insurance Customer Intangible [Member]
Finite-Lived Intangible Assets, Gross [Abstract]
Beginning balance	1,067	1,067	1,067
Ending balance	1,067	1,067	1,067
Accumulated amortization:
Beginning balance	(597)	(445)	(293)
Amortization	(152)	(152)	(152)
Ending balance	(749)	(597)	(445)
Net intangible assets	318	$ 470	$ 622
Customer Relationships [Member] | Insurance Customer Intangible [Member] | BSPR
Finite-Lived Intangible Assets, Gross [Abstract]
Additions due to acquisitions	$ 0