GOODWILL AND OTHER INTANGIBLES - Gross Amount and Accumulated Amortization of Other Intangible Assets (Detail) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2018	Dec. 31, 2019
Core Deposits [Member]
Finite Lived Intangible Assets [Line Items]
Gross amount	$ 51,664		$ 51,664
Accumulated amortization	(48,578)		(48,176)
Net carrying amount	$ 3,086		3,488
Remaining amortization period	4 years 7 months 6 days	5 years 1 month 6 days
Customer Relationships [Member] | Credit Card [Member]
Finite Lived Intangible Assets [Line Items]
Gross amount	$ 24,465		24,465
Accumulated amortization	(21,797)		(20,850)
Net carrying amount	$ 2,668		3,615
Remaining amortization period	1 year 4 months 24 days	1 year 10 months 24 days
Customer Relationships [Member] | Insurance Customer Intangible [Member]
Finite Lived Intangible Assets [Line Items]
Gross amount	$ 1,067		1,067
Accumulated amortization	(673)		(597)
Net carrying amount	$ 394		$ 470
Remaining amortization period	2 years 6 months	3 years