Investment securities (Tables)

3 Months Ended

Mar. 31, 2020

Investments, Debt and Equity Securities [Abstract]

Summary of Amortized Cost of Securities and Fair Values

The following table summarizes the amortized cost, allowance for credit losses and fair value of the available-for-sale debt securities and the corresponding amounts of unrealized gains and losses recognized in accumulated other comprehensive income at March 31, 2020 and December 31, 2019:

	March 31, 2020
	Amortized cost		Gross unrealized gains		Gross unrealized losses			Allowance for credit losses for investments		Fair Value
Investment Securities
Available-for-sale debt securities
U.S. government agency securities	$	3,007	$	30	$	—		$	—	$	3,037
Mortgage-backed securities - residential	481,651		18,028		(21		)	—		499,658
Municipals, tax exempt	226,026		10,010		(359		)	—		235,677
Treasury securities	24,488		372		—			—		24,860
Corporate securities	1,000		—		(15		)	—		985
Total	$	736,172	$	28,440	$	(395	)	$	—	$	764,217

	December 31, 2019
	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair Value
Investment Securities
Available-for-sale debt securities
Mortgage-backed securities - residential	$	487,101	$	5,236	$	(1,661	)	$	490,676
Municipals, tax exempt	181,178		8,287		(230		)	189,235
Treasury securities	7,426		22		—			7,448
Corporate securities	1,000		22		—			1,022
Total	$	676,705	$	13,567	$	(1,891	)	$	688,381

Schedule of Amortized Cost and Fair Value of Debt Securities by Contractual Maturity

Therefore, mortgage-backed securities are not included in the maturity categories in the following maturity summary.

	March 31,				December 31,
	2020				2019
	Available-for-sale				Available-for-sale
	Amortized cost		Fair value		Amortized cost		Fair value
Due in one year or less	$	17,075	$	17,168	$	1,148	$	1,152
Due in one to five years	36,509		36,740		11,553		11,676
Due in five to ten years	27,580		28,112		18,287		18,887
Due in over ten years	173,357		182,539		158,616		165,990
	254,521		264,559		189,604		197,705
Mortgage-backed securities - residential	481,651		499,658		487,101		490,676
Total debt securities	$	736,172	$	764,217	$	676,705	$	688,381

Summary of Summary of Sales and Other Dispositions of Available-for-Sale Securities

Sales and other dispositions of available-for-sale securities were as follows:

	Three Months Ended March 31,
	2020		2019
Proceeds from sales	$	—	$	1,758
Proceeds from maturities, prepayments and calls	27,657		20,814
Gross realized gains	—		1
Gross realized losses	—		7

Schedule of Gross Unrealized Losses

The following tables show gross unrealized losses for which an allowance for credit losses has not been recorded at March 31, 2020 and December 31, 2019, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position:

	March 31, 2020
	Less than 12 months					12 months or more				Total
	Fair Value		Unrealized Loss			Fair Value		Unrealized Loss		Fair Value		Unrealized loss
Mortgage-backed securities - residential	$	1,481	$	(21	)	$	—	$	—	$	1,481	$	(21	)
Municipals, tax exempt	39,482		(359		)	—		—		39,482		(359		)
Corporate securities	985		(15		)	—		—		985		(15		)
Total	$	41,948	$	(395	)	$	—	$	—	$	41,948	$	(395	)

	December 31, 2019
	Less than 12 months					12 months or more					Total
	Fair Value		Unrealized Loss			Fair Value		Unrealized Loss			Fair Value		Unrealized loss
Mortgage-backed securities - residential	$	47,641	$	(164	)	$	175,730	$	(1,497	)	$	223,371	$	(1,661	)
Municipals, tax exempt	15,433		(230		)	—		—			15,433		(230		)
Treasury securities	—		—			—		—			—		—
Total	$	63,074	$	(394	)	$	175,730	$	(1,497	)	$	238,804	$	(1,891	)