Investment and Equity Securities - Allowance for Credit Losses on Held to Maturity Securities (Detail) $ in Thousands	6 Months Ended
Jun. 30, 2026 USD ($)
Debt Securities, Held-to-Maturity, Allowance for Credit Loss [Line Items]
Balance, December 31, 2025	$ 45
Provision for (recovery of) credit losses	(1)
Balance, March 31, 2026	44
Corporate Bonds [Member]
Debt Securities, Held-to-Maturity, Allowance for Credit Loss [Line Items]
Balance, December 31, 2025	45
Provision for (recovery of) credit losses	(1)
Balance, March 31, 2026	$ 44

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.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-13

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3D
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-3D

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3C
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-3C

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration