Fair Value Measurement and fair Value of Financial Instruments - Carrying Values and Fair Values of Financial Instruments (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Financial Assets:
Investment securities held to maturity, Carrying Value	$ 115,752	$ 123,975
Investment securities held to maturity, fair value	119,023	124,904
Federal Home Loan Bank and other membership bank stocks, Carrying Value	28,575	22,505
Federal Home Loan Bank and other membership bank stocks, Fair Value	28,575	22,505
Loans, net Carrying Value	5,279,739	5,097,820
Loans, net Fair Value	5,229,776	5,194,065
Financial Liabilities:
Certificates of deposit, Carrying value	1,084,046	870,804
Certificates of deposit, Fair Value	1,084,580	871,418
Other borrowings, Carrying value	140,715	165,816
Other borrowings, Fair Value	144,658	166,505
Subordinated debentures, Carrying Value	118,229	118,220
Subordinated debentures, Fair Value	112,272	117,992
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	116,448	121,503
Federal Home Loan Bank and other membership bank stocks, Fair Value	28,575	22,505
Loans, net Fair Value	0	0
Financial Liabilities:
Certificates of deposit, Fair Value	1,084,580	871,418
Other borrowings, Fair Value	144,658	166,505
Subordinated debentures, Fair Value	0	0
Significant Unobservable Inputs (Level 3)
Financial Assets:
Investment securities held to maturity, fair value	2,575	3,401
Federal Home Loan Bank and other membership bank stocks, Fair Value	0	0
Loans, net Fair Value	5,229,776	5,194,065
Financial Liabilities:
Certificates of deposit, Fair Value	0	0
Other borrowings, Fair Value	0	0
Subordinated debentures, Fair Value	$ 112,272	$ 117,992

Certificate of deposits 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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Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements and loans held for sale.

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