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Investment Securities - Proceeds from Sale, Gross Gains (Losses) Realized on Sales, Maturities and Other-Than-Temporary Impairment Charges Related to Securities Available for Sale (Detail) - USD ($) $ in Thousands | 3 Months Ended
--- | ---
Mar. 31, 2018 | Mar. 31, 2017
Investments, Debt and Equity Securities [Abstract] |  |
Proceeds from Sale of Available-for-sale Securities | $ 0 | $ 0
Sales Transactions: |  |
Gross gains | 0 | 0
Gross losses | 0 | 0
Available-for-sale Securities, Gross Realized Gain (Loss), Excluding Other than Temporary Impairments | 0 | 0
Maturities and impairment |  |
Gross Gains | 2,840 | 652
Gross Losses | 0 | 0
Gain Losses Maturities And Impairment | 2,840 | 652
Net gains and impairment | $ 2,840 | $ 652

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- Definition Gain losses maturities and impairment. + References No definition available. + Details
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- Definition This item represents the gross gain on maturities of available for sale securities. + References No definition available. + Details
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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 Maturities and impairment. + References No definition available. + Details
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- Definition Net gains and impairment. + 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 Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 9 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27357-111563 + Details
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- Definition This item represents the gross loss realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 9 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27357-111563 + Details
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- Definition This item represents the difference between the gross realized gains and losses realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=82896770&loc=d3e26805-111562 + 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://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=82896770&loc=d3e26853-111562 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 12 -Subparagraph (a),(b) -URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3179-108585 + Details
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