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INVESTMENTS (Narrative) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Schedule of Investments [Line Items]
Net unrealized gain on available-for-sale debt securities, net of tax	$ 28,724	$ 7,484	$ 28,724	$ 7,484	$ 3,250	$ (17,826)
Deferred tax assets, unrealized losses on available for sale securities	$ 7,900		$ 7,900		$ 890
Unrealized Loss as a Percent of Fair Value	1.00%		1.00%		1.00%
Security pledged as collateral, amortized cost	$ 597,700		$ 597,700		$ 709,000
Security pledged as collateral, fair value	622,600		622,600		$ 712,400
Unrealized gain (loss), change in fair value of bank stock equity securities	$ 0	$ 22	$ 0	$ (62)

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Security Owned and Pledged as Collateral, Amortized Cost

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Unrealized Loss as a Percent of Fair Value

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Amount, after tax, of accumulated unrealized gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 14
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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from unrealized losses on available-for-sale securities.

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-Publisher FASB
-Name Accounting Standards Codification
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Amount of unrealized gain (loss) on investment in marketable security.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Fair value of financial instrument held by the entity for its own account (proprietary securities) for trading or investment purposes that are carried at fair value and pledged to counterparties as collateral for financing transactions.

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