| Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Non-Recurring Basis (Parenthetical) (Detail) - USD ($) $ in Thousands | Sep. 30, 2023 | Dec. 31, 2022 | 
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| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
| Loans receivable | $ 5,953,472 | $ 5,895,610 | 
| Non-recurring Basis | Real estate loans | ||
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
| Loans receivable | 2,000 | $ 2,700 | 
| Non-recurring Basis | Commercial and Industrial Loans | ||
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
| Loans receivable | $ 4,800 | 
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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. Reference 1: http://www.xbrl.org/2003/role/disclosureRef 
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- Definition Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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