Investment Securities - Summary of securities sales activity (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Proceeds from sales	$ 352,106	$ 168,891	$ 340,540
Gross gains on sales	1,843	2,082	1,247
Gross losses on sales	(2,864)	(2,738)	(1,205)
Net (losses) gains on sales of securities	(1,021)	(656)	42
Income tax (benefit) expense attributable to sales	$ (247)	$ (132)	$ 14

Amount of realized gain on 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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-Publisher FASB
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Amount of realized gain (loss) on 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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Amount of tax expense (benefit) of reclassification adjustment from accumulated other comprehensive income for unrealized gain (loss) realized upon the sale of available-for-sale securities.

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Amount of cash inflow from sale 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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