Fair Value Measurements - Assets and liabilities recorded at fair value on recurring basis (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Investment securities available-for-sale, at fair value	$ 858,916	$ 843,363
Derivative asset	3,165	311
Derivative liability	6,459	611
U. S. agency securities
Investment securities available-for-sale, at fair value	147,759	179,794
Residential mortgage backed securities
Investment securities available-for-sale, at fair value	547,388	543,852
Loans held for sale	60,036	52,927
Municipal bonds
Investment securities available-for-sale, at fair value	75,588	73,931
Corporate bonds
Investment securities available-for-sale, at fair value	52,984	10,733
U.S. Treasury
Investment securities available-for-sale, at fair value	34,999	34,855
Recurring
Loans held for sale	60,036	56,707
Other equity investments	198	198
Assets measured at a fair value	919,600	900,667
Derivative liability	152		$ 86
Liabilities measured at a fair value	6,424	667
Recurring \| Interest Rate Swap
Derivative liability	1,695		203
Recurring \| Interest Rate Caps
Derivative asset	317	317
Derivative liability	2,975		312
Recurring \| U. S. agency securities
Investment securities available-for-sale, at fair value	147,759	179,794
Recurring \| Residential mortgage backed securities
Investment securities available-for-sale, at fair value	547,388	543,852
Recurring \| Municipal bonds
Investment securities available-for-sale, at fair value	75,588	73,931
Recurring \| Corporate bonds
Investment securities available-for-sale, at fair value	52,984	10,733
Recurring \| U.S. Treasury
Investment securities available-for-sale, at fair value	34,999	34,855
Recurring \| Mortgage Banking Derivative \| Derivative Financial Instruments, Liability
Derivative liability	1,602	66
Recurring \| Mortgage Banking Derivative \| Derivative Financial Instruments, Assets
Derivative asset	331	280
Recurring \| Fair Value, Inputs, Level 2
Loans held for sale	60,036	56,707
Assets measured at a fair value	866,087	889,456
Derivative liability	152		86
Liabilities measured at a fair value	4,822	601
Recurring \| Fair Value, Inputs, Level 2 \| Interest Rate Swap
Derivative liability	1,695		203
Recurring \| Fair Value, Inputs, Level 2 \| Interest Rate Caps
Derivative asset	317	317
Derivative liability	2,975		$ 312
Recurring \| Fair Value, Inputs, Level 2 \| U. S. agency securities
Investment securities available-for-sale, at fair value	147,759	179,794
Recurring \| Fair Value, Inputs, Level 2 \| Residential mortgage backed securities
Investment securities available-for-sale, at fair value	547,388	543,852
Recurring \| Fair Value, Inputs, Level 2 \| Municipal bonds
Investment securities available-for-sale, at fair value	75,588	73,931
Recurring \| Fair Value, Inputs, Level 2 \| U.S. Treasury
Investment securities available-for-sale, at fair value	34,999	34,855
Recurring \| Fair Value, Inputs, Level 3
Other equity investments	198	198
Assets measured at a fair value	53,513	11,211
Liabilities measured at a fair value	1,602	66
Recurring \| Fair Value, Inputs, Level 3 \| Corporate bonds
Investment securities available-for-sale, at fair value	52,984	10,733
Recurring \| Fair Value, Inputs, Level 3 \| Mortgage Banking Derivative \| Derivative Financial Instruments, Liability
Derivative liability	1,602	66
Recurring \| Fair Value, Inputs, Level 3 \| Mortgage Banking Derivative \| Derivative Financial Instruments, Assets
Derivative asset	$ 331	$ 280

Fair value portion of other equity investments.

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- Definition

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, 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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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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