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Derivative financial instruments - Information about Fair Values of Derivative Instruments in Consolidated Statement of Income (Detail) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2025 | Sep. 30, 2024 | Sep. 30, 2025 | Sep. 30, 2024
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Derivatives not designated as hedging instruments, derivatives | $ 16,000 | $ 10,000 | $ 34,000 | $ 24,000
Interest rate swap agreements | Designated as Hedging Instrument | Fair value hedges: |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Derivatives in fair value hedging relationships, derivative | 13,000 | 130,000 | 160,000 | 52,000
Derivatives in fair value hedging relationships, hedged item | $ (13,000) | $ (130,000) | $ (160,000) | $ (52,000)
Interest rate swap agreements | Fixed Rate Long-Term Borrowings | Designated as Hedging Instrument | Fair value hedges: |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Derivative, gain (loss), statement of income or comprehensive income [extensible enumeration] | Other costs of operations | Other costs of operations | Other costs of operations | Other costs of operations
Derivatives in fair value hedging relationships, derivative | $ 13,000 | $ 130,000 | $ 160,000 | $ 52,000
Derivatives in fair value hedging relationships, hedged item | (13,000) | (130,000) | (160,000) | (52,000)
Interest rate swap agreements | Fixed Rate Available For Sale Securities | Designated as Hedging Instrument | Fair value hedges: |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Derivatives in fair value hedging relationships, derivative |  |  |  | 0
Derivatives in fair value hedging relationships, hedged item |  |  |  | 0
Interest Rate Contracts |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Derivatives not designated as hedging instruments, derivatives | 11,000 | 5,000 | 23,000 | 11,000
Foreign exchange and other option and futures contracts |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Derivatives not designated as hedging instruments, derivatives | $ 5,000 | $ 5,000 | $ 11,000 | $ 13,000

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- Definition Amount of increase (decrease) in the fair value of derivatives recognized in the income statement. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4A -Subparagraph (b)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4A Reference 2: http://www.xbrl.org/2003/role/exampleRef -Name Accounting Standards Codification -Section 55 -Paragraph 10 -SubTopic 10 -Topic 825 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482881/825-10-55-10 + Details
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- Definition Line items represent financial concepts included in a table. 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