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Investments - Changes in Allowance for Credit Losses by Major Security Type of Investments Classified as Held-to-Maturity (Detail) - USD ($) $ in Thousands | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2020 | Jun. 30, 2020
Schedule Of Held To Maturity Securities [Line Items] |  |
Balance | $ 275 | $ 301
Provision for credit loss expense (benefit) | 82 | 56
Balance | 357 | 357
States and Political Subdivisions [Member] |  |
Schedule Of Held To Maturity Securities [Line Items] |  |
Balance | 50 | 45
Provision for credit loss expense (benefit) | (1) | 4
Balance | 49 | 49
Corporate Bonds [Member] |  |
Schedule Of Held To Maturity Securities [Line Items] |  |
Balance | 215 | 245
Provision for credit loss expense (benefit) | 84 | 54
Balance | 299 | 299
Asset-Backed Securities [Member] |  |
Schedule Of Held To Maturity Securities [Line Items] |  |
Balance | 10 | 11
Provision for credit loss expense (benefit) | (1) | (2)
Balance | $ 9 | $ 9

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- Definition Securities held to maturity allowance for credit loss. + References No definition available. + Details
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- Definition Amount of expense (reversal of expense) for expected credit loss on 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 326 -SubTopic 20 -Section 50 -Paragraph 13 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919249-210447 + Details
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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