Fair Value Measurements - Assets and liabilities recorded at fair value on recurring basis (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Investment securities available-for-sale, at fair value	$ 843,363	$ 784,139
Loans held for sale	56,707	19,254
Other equity investments	198	218
Derivative asset	311
Assets measured at a fair value	900,667	807,349
Derivative liability	611
Liabilities measured at a fair value	667	269
Derivative Financial Instruments, Liability [Member]
Derivative liability	86
Interest Rate Swap
Derivative asset		3,727
Derivative liability	203
Interest Rate Caps
Derivative liability	312
U. S. agency securities
Investment securities available-for-sale, at fair value	179,794	256,345
Residential mortgage backed securities
Investment securities available-for-sale, at fair value	543,852	472,231
Loans held for sale	52,927	19,254
Municipal bonds
Investment securities available-for-sale, at fair value	73,931	45,769
Corporate bonds
Investment securities available-for-sale, at fair value	10,733	9,576
U.S. Treasury
Investment securities available-for-sale, at fair value	34,855
Mortgage Banking Derivative
Derivative asset	280	229
Derivative liability	66	269
Fair Value, Inputs, Level 2 [Member]
Investment securities available-for-sale, at fair value	832,432	774,345
Loans held for sale	56,707	19,254
Derivative liability	86
Liabilities measured at a fair value	601
Fair Value, Inputs, Level 2 [Member] \| Recurring [Member]
Assets measured at a fair value	889,456	797,326
Fair Value, Inputs, Level 2 [Member] \| Derivative Financial Instruments, Liability [Member]
Derivative liability	86
Fair Value, Inputs, Level 2 [Member] \| Interest Rate Swap
Derivative asset		3,727
Derivative liability	203
Fair Value, Inputs, Level 2 [Member] \| Interest Rate Caps
Derivative asset	280
Derivative liability	312
Fair Value, Inputs, Level 2 [Member] \| U. S. agency securities
Investment securities available-for-sale, at fair value	179,794	256,345
Fair Value, Inputs, Level 2 [Member] \| Residential mortgage backed securities
Investment securities available-for-sale, at fair value	543,852	472,231
Fair Value, Inputs, Level 2 [Member] \| Municipal bonds
Investment securities available-for-sale, at fair value	73,931	45,769
Fair Value, Inputs, Level 2 [Member] \| U.S. Treasury
Investment securities available-for-sale, at fair value	34,855
Fair Value, Inputs, Level 3 [Member]
Investment securities available-for-sale, at fair value	10,931	9,794
Other equity investments	198	218
Fair Value, Inputs, Level 3 [Member] \| Recurring [Member]
Assets measured at a fair value	11,211	10,023
Liabilities measured at a fair value	66	269
Fair Value, Inputs, Level 3 [Member] \| Corporate bonds
Investment securities available-for-sale, at fair value	10,733	9,576
Fair Value, Inputs, Level 3 [Member] \| Mortgage Banking Derivative
Derivative asset	280	229
Derivative liability	$ 66	$ 269

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Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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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 financial and nonfinancial obligations.

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Fair value portion of loans held-for-sale including, but not limited to, mortgage loans and finance receivables.

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