Fair Value Measurements - Fair Value on Balance Sheet (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Financial assets:
Debt securities available for sale, at fair value	$ 1,099,801	$ 1,032,868
Debt securities held to maturity	303,179	254,841
Equity securities	1,915	1,890
Loans held-for-sale	2,000	8,100
Quoted Prices in Active Markets for Identical Assets (Level 1)
Financial assets:
Cash and cash equivalents	54,377	42,201
Debt securities available for sale, at fair value	50,261	54,157
Debt securities held to maturity	38,521	23,241
Equity securities	1,915	1,890
Federal Home Loan Bank stock	0	0
Loans held-for-sale	0	0
Loans receivable, net	0	0
Derivative assets	0	0
Deposits
Deposits	0	0
Borrowings	0	0
Derivative liabilities	0	0
Significant Other Observable Inputs (Level 2)
Financial assets:
Cash and cash equivalents	0	0
Debt securities available for sale, at fair value	1,049,540	978,711
Debt securities held to maturity	264,658	231,600
Equity securities	0	0
Federal Home Loan Bank stock	58,613	58,938
Loans held-for-sale	2,044	8,081
Loans receivable, net	0	0
Derivative assets	4,227	1,342
Deposits
Deposits	4,672,763	4,402,336
Borrowings	1,166,752	1,185,007
Derivative liabilities	16,532	3,944
Significant Unobservable Inputs (Level 3)
Financial assets:
Cash and cash equivalents	0	0
Debt securities available for sale, at fair value	0	0
Debt securities held to maturity	0	0
Equity securities	0	0
Federal Home Loan Bank stock	0	0
Loans held-for-sale	0	0
Loans receivable, net	5,089,413	4,841,830
Derivative assets	0	0
Deposits
Deposits	0	0
Borrowings	0	0
Derivative liabilities	0	0
Carrying Value
Financial assets:
Cash and cash equivalents	54,377	42,201
Debt securities available for sale, at fair value	1,099,801	1,032,868
Debt securities held to maturity	299,605	262,143
Equity securities	1,915	1,890
Federal Home Loan Bank stock	58,613	58,938
Loans held-for-sale	2,044	8,081
Loans receivable, net	5,050,771	4,916,840
Derivative assets	4,227	1,342
Deposits
Deposits	4,668,645	4,413,873
Borrowings	1,163,271	1,189,180
Derivative liabilities	16,532	3,944
Total Fair Value
Financial assets:
Cash and cash equivalents	54,377	42,201
Debt securities available for sale, at fair value	1,099,801	1,032,868
Debt securities held to maturity	303,179	254,841
Equity securities	1,915	1,890
Federal Home Loan Bank stock	58,613	58,938
Loans held-for-sale	2,044	8,081
Loans receivable, net	5,089,413	4,841,830
Derivative assets	4,227	1,342
Deposits
Deposits	4,672,763	4,402,336
Borrowings	1,166,752	1,185,007
Derivative liabilities	$ 16,532	$ 3,944

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 portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

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Fair value portion of deposit liabilities held by the entity, including, but not limited to, foreign and domestic, interest and noninterest bearing, demand deposits, saving deposits, negotiable orders of withdrawal (NOW) and time deposits.

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Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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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 loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

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The face amount of loans that will be sold to other entities.

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