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GOODWILL AND OTHER INTANGIBLES - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019
Finite Lived Intangible Assets [Line Items]
Goodwill	$ 38,611		$ 38,611		$ 38,632	$ 28,098
Amortization			8,652	$ 2,912
Goodwill and Intangible Asset Impairment			0
Intangible assets	32,689		32,689		40,893
United States Operations Segment [Member]
Finite Lived Intangible Assets [Line Items]
Goodwill	28,098		28,098		28,098	$ 28,098
Core Deposits [Member]
Finite Lived Intangible Assets [Line Items]
Amortization	1,900	$ 800	5,800	1,200
Intangible assets	30,494		30,494		35,842
Customer Relationships [Member] \| Credit Card [Member]
Finite Lived Intangible Assets [Line Items]
Amortization	900	700	2,700	1,600
Intangible assets	1,992		1,992		4,733
Customer Relationships [Member] \| Insurance Customer Intangible [Member]
Finite Lived Intangible Assets [Line Items]
Amortization	38	$ 39	100	$ 100
Intangible assets	203		203		$ 318
Santander [Member]
Finite Lived Intangible Assets [Line Items]
Goodwill	$ 10,500		$ 10,500