SECURITIES AVAILABLE FOR SALE - Summary of Amortized Cost and Fair Value and Corresponding Amounts of Gross Unrealized Gains and Losses (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 469,607	$ 411,706
Gross Unrealized Gains	2,432	7,496
Gross Unrealized Losses	6,195	3,894
Fair Value	465,844	415,308
States and political subdivisions
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	144,596	153,803
Gross Unrealized Gains	1,919	6,133
Gross Unrealized Losses	1,511	478
Fair Value	145,004	159,458
GSE residential MBSs
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		48,600
Gross Unrealized Gains		930
Gross Unrealized Losses		0
Fair Value		49,530
GSE residential CMOs
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	110,421	113,658
Gross Unrealized Gains	332	296
Gross Unrealized Losses	2,689	2,835
Fair Value	108,064	111,119
Private label residential CMOs
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	144	999
Gross Unrealized Gains	0	4
Gross Unrealized Losses	1	0
Fair Value	143	1,003
Private label commercial CMOs
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	75,911	7,809
Gross Unrealized Gains	55	0
Gross Unrealized Losses	921	156
Fair Value	75,045	7,653
Asset-backed and other
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	138,535	86,837
Gross Unrealized Gains	126	133
Gross Unrealized Losses	1,073	425
Fair Value	$ 137,588	$ 86,545

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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) 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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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-Topic 320
-SubTopic 10
-Section 50
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Amortized cost of 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/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
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Amount of 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/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109979856&loc=d3e26610-111562

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