Securities - Fair Value and Amortized Cost of Debt Securities by Contractual Maturity (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Investments Debt And Equity Securities [Abstract]
Available-for-Sale, Amortized Cost, Within one year	$ 8,192
Available-for-Sale, Amortized Cost, One to five years	98,660
Available-for-Sale, Amortized Cost, Five to ten years	301,043
Available-for-Sale, Amortized Cost, After ten years	81,819
Available-for-Sale, Amortized Cost, Mortgage-backed securities	835,301
Available-for-Sale, Amortized Cost	1,325,015	$ 845,401
Available-for-Sale, Fair Value, Within one year	8,260
Available-for-Sale, Fair Value, One to five years	98,570
Available-for-Sale, Fair Value, Five to ten years	300,490
Available-for-Sale, Fair Value, After ten years	83,547
Available-for-Sale, Fair Value, Mortgage-backed securities	836,575
Available-for-Sale, Fair Value, Total debt securities	$ 1,327,442	$ 871,827

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in second through fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Fair value of securitized, pay-through debt securities collateralized by real estate mortgage loans classified as available-for-sale.

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