Fair Value Measurement and Fair Value of Financial Instruments - Carrying Values and Fair Values of Company's Financial Instruments (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Financial Assets:
Investment securities held to maturity, fair value	$ 93,868	$ 124,904
Investment securities held to maturity	90,766	123,975
Federal Home Loan Bank and other membership bank stocks, Fair Value	11,979	22,505
Federal Home Loan Bank and other membership bank stocks, Carrying Value	11,979	22,505
Loans, net, Fair Value	5,939,413	5,194,065
Loans, net, Carrying Value	5,950,108	5,097,820
Financial Liabilities:
Certificates of deposit, Fair Value	1,077,620	871,418
Certificates of deposit, Carrying Value	1,078,256	870,804
Other borrowings, Fair Value	25,206	166,505
Other borrowings, Carrying Value	25,000	165,816
Subordinated debentures, Fair Value	118,208	117,992
Subordinate debentures, Carrying Value	118,257	118,220
Quoted Prices in Active Markets for Identical Assets (Level 1)
Financial Assets:
Investment securities held to maturity, fair value	0	0
Federal Home Loan Bank and other membership bank stocks, Fair Value	0	0
Loans, net, Fair Value	0	0
Financial Liabilities:
Certificates of deposit, Fair Value	0	0
Other borrowings, Fair Value	0	0
Subordinated debentures, Fair Value	0	0
Significant Other Observable Inputs (Level 2)
Financial Assets:
Investment securities held to maturity, fair value	93,868	121,503
Federal Home Loan Bank and other membership bank stocks, Fair Value	11,979	22,505
Loans, net, Fair Value	0	0
Financial Liabilities:
Certificates of deposit, Fair Value	1,077,620	871,418
Other borrowings, Fair Value	25,206	166,505
Subordinated debentures, Fair Value	0	0
Significant Unobservable Inputs (Level 3)
Financial Assets:
Investment securities held to maturity, fair value	0	3,401
Federal Home Loan Bank and other membership bank stocks, Fair Value	0	0
Loans, net, Fair Value	5,939,413	5,194,065
Financial Liabilities:
Certificates of deposit, Fair Value	0	0
Other borrowings, Fair Value	0	0
Subordinated debentures, Fair Value	$ 118,208	$ 117,992

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Other Borrowings Fair Value Disclosure

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Fair value of subordinated debt obligations including, but not limited to, subordinated loan, subordinated bond, subordinated debenture or junior debt.

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Federal Home Loan Bank (FHLB) stock represents an equity interest in a FHLB. It does not have a readily determinable fair value because its ownership is restricted and it lacks a market (liquidity).

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Amount of investment in debt security measured at amortized cost (held-to-maturity).

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Fair value of investment in debt security measured at amortized cost (held-to-maturity).

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Fair value portion of investments in Federal Home Loan Bank (FHLBank) stock.

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Fair value portion of an agreement for an unconditional promise by the maker to pay the holder a definite sum of money at a future date.

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Amount, after allowance for credit loss, of financing receivable. Excludes financing receivable covered under loss sharing agreement.

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The carrying amount as of the balance sheet date for the aggregate of other miscellaneous borrowings owed by the reporting entity.

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Including the current and noncurrent portions, carrying value as of the balance sheet date of subordinated debt (with initial maturities beyond one year or beyond the operating cycle if longer). Subordinated debt places a lender in a lien position behind debt having a higher priority of repayment in liquidation of the entity's assets.

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Amount of time deposit liabilities, including certificates of deposit.

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