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Investment Securities - Additional Information (Detail) - USD ($) $ in Thousands | 9 Months Ended |
--- | --- | ---
Sep. 30, 2018 | Sep. 30, 2017 | Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract] |  |  |
Available-for-sale Securities, Gross Realized Gains | $ 4,719 | $ 359 |
Gross Losses | 0 | 60 |
Gross Gains | 3,383 | 712 |
Debt Securities, Held-to-maturity, Restricted | 298,900 |  | $ 338,300
Proceeds from Sale of Available-for-sale Securities | 15,939 | $ 143,660 |
Debt Securities, Available-for-sale, Restricted | $ 680,900 |  | $ 569,000

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- Definition This item represents the gross loss on maturities of available for sale securities. + References No definition available. + Details
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- Definition This item represents the gross profit realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities. + References No definition available. + Details
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- Definition Amount of restricted 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 860 -SubTopic 30 -Section 50 -Paragraph 1A -Subparagraph (b)(1)(i) -URI http://asc.fasb.org/extlink&oid=109249958&loc=SL6224234-111729 + Details
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- Definition Amount of restricted 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 860 -SubTopic 30 -Section 50 -Paragraph 1A -Subparagraph (b)(1)(i) -URI http://asc.fasb.org/extlink&oid=109249958&loc=SL6224234-111729 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 10 -Section S99 -Paragraph 3 -Subparagraph (SX 210.6-03(f)) -URI http://asc.fasb.org/extlink&oid=6488002&loc=d3e600178-122990 + Details
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- Definition The cash inflow associated with the sale of debt and equity securities classified as available-for-sale securities. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=109979856&loc=d3e26853-111562 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 12 -Subparagraph (a),(b) -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3179-108585 + Details
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