GOODWILL AND OTHER INTANGIBLES - Additional Information (Detail) - USD ($) $ in Thousands		3 Months Ended	12 Months Ended
	Sep. 01, 2020	Dec. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Finite Lived Intangible Assets [Line Items]
Goodwill		$ 38,632	$ 38,632	$ 28,098
Additions to goodwill			6,303
Adjustments to goodwill			4,231
Total purchase price consideration (cash)			1,280,424	0	$ 0
Intangibles		40,900	40,900
Goodwill impairment			0	0	0
Net intangible assets		40,893	40,893	7,573	10,659
FL
Finite Lived Intangible Assets [Line Items]
Goodwill		28,100	$ 28,100
Minimum [Member]
Finite Lived Intangible Assets [Line Items]
Weighted average amortization period			1 year
Maximum [Member]
Finite Lived Intangible Assets [Line Items]
Weighted average amortization period			6 years
Core Deposits [Member]
Finite Lived Intangible Assets [Line Items]
Intangibles		35,800	$ 35,800
Net intangible assets		35,842	35,842	3,488	4,335
Customer Relationships [Member] | Credit Card [Member]
Finite Lived Intangible Assets [Line Items]
Intangibles		4,700	4,700
Net intangible assets		4,733	4,733	3,615	5,702
Customer Relationships [Member] | Insurance Customer Intangible [Member]
Finite Lived Intangible Assets [Line Items]
Intangibles		300	300
Net intangible assets		318	318	$ 470	$ 622
BSPR
Finite Lived Intangible Assets [Line Items]
Goodwill	$ 10,500
Additions to goodwill	6,300
Adjustments to goodwill	4,200	4,200
Additions due to acquisitions			39,232
Total purchase price consideration (cash)	1,300
Intangibles	39,200
BSPR | Core Deposits [Member]
Finite Lived Intangible Assets [Line Items]
Additions due to acquisitions			35,432
Intangibles	35,400
BSPR | Customer Relationships [Member] | Credit Card [Member]
Finite Lived Intangible Assets [Line Items]
Additions due to acquisitions			3,800
Intangibles	$ 3,800
Net intangible assets		$ 3,000	3,000
BSPR | Customer Relationships [Member] | Insurance Customer Intangible [Member]
Finite Lived Intangible Assets [Line Items]
Additions due to acquisitions			$ 0