INVESTMENT SECURITIES - Investment Securities Held to Maturity (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Schedule Of Held To Maturity Securities [Line Items]
Held To Maturity Securities	$ 150,627	$ 156,190
Held To Maturity Securities Fair Value	131,032	132,759
US States And Political Subdivisions [Member] \| Puerto Rico [Member]
Schedule Of Held To Maturity Securities [Line Items]
Held To Maturity Securities	150,627	156,190
Held To Maturity Securities Accumulated Unrecognized Holding Gain	0	0
Held To Maturity Securities Accumulated Unrecognized Holding Loss	19,595	23,431
Held To Maturity Securities Fair Value	$ 131,032	$ 132,759
Held To Maturity Securities Debt Maturities Average Yield	5.03%	4.73%
US States And Political Subdivisions [Member] \| After One To Five Years [Member] \| Puerto Rico [Member]
Schedule Of Held To Maturity Securities [Line Items]
Held To Maturity Securities	$ 3,853	$ 1,136
Held To Maturity Securities Accumulated Unrecognized Holding Gain	0	0
Held To Maturity Securities Accumulated Unrecognized Holding Loss	173	20
Held To Maturity Securities Fair Value	$ 3,680	$ 1,116
Held To Maturity Securities Debt Maturities Average Yield	5.38%	5.38%
US States And Political Subdivisions [Member] \| After Five To Ten Years [Member] \| Puerto Rico [Member]
Schedule Of Held To Maturity Securities [Line Items]
Held To Maturity Securities	$ 39,523	$ 10,741
Held To Maturity Securities Accumulated Unrecognized Holding Gain	0	0
Held To Maturity Securities Accumulated Unrecognized Holding Loss	3,048	718
Held To Maturity Securities Fair Value	$ 36,475	$ 10,023
Held To Maturity Securities Debt Maturities Average Yield	5.28%	4.47%
US States And Political Subdivisions [Member] \| After Ten Years [Member] \| Puerto Rico [Member]
Schedule Of Held To Maturity Securities [Line Items]
Held To Maturity Securities	$ 107,251	$ 144,313
Held To Maturity Securities Accumulated Unrecognized Holding Gain	0	0
Held To Maturity Securities Accumulated Unrecognized Holding Loss	16,374	22,693
Held To Maturity Securities Fair Value	$ 90,877	$ 121,620
Held To Maturity Securities Debt Maturities Average Yield	4.93%	4.74%

Percentage of weighted average yield of held to maturity securities.

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- Definition

Amount after other than temporary impairment (OTTI) accretion, of investments in debt securities classified as held-to-maturity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27232-111563

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=75030427&loc=d3e22054-111558

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27232-111563

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.1)
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.6)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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Amount of accumulated unrealized gain on investments in debt securities classified as held-to-maturity.

+ References

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Amount of accumulated unrealized loss on investments in debt securities classified as held-to-maturity.

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Fair value of investments in debt securities classified as held-to-maturity.

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