Securities - Carrying Value of Held-to-Maturity Investment Securities (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Amortized Cost	$ 851,903	$ 772,060
Net loss on date of transfer from available-for-sale	(13,347)	(13,347)
Accretion of unrealized loss on securities reclassified to held-to-maturity	8,254	5,349
Carrying value	$ 846,810	$ 764,062

Unrealized holding gain (loss) related to transfers of securities into held-to-maturity classification and out of the available-for-sale classification.

No definition available.

+ Details

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- Definition

Other comprehensive income reclassification of accretion of net unrealized losses to held to maturity securities.

+ References

No definition available.

+ Details

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- Definition

Amount of investment in debt security measured at amortized cost (held-to-maturity).

+ 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

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-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

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- Definition

Amount, before other-than-temporary impairment (OTTI) accretion, of investment in debt securities measured at amortized cost (held-to-maturity).

+ References

No definition available.

+ Details

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- References

No definition available.

+ Details

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