Investment securities (Tables)

6 Months Ended

Jun. 30, 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 June 30, 2020 and December 31, 2019: 

	June 30, 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	$	3,003	$	21	$	—	$	—	$	3,024
Mortgage-backed securities - residential	439,843		14,770		(7)		—		454,606
Municipals, tax exempt	251,424		14,875		(247)		—		266,052
Treasury securities	22,485		286		—		—		22,771
Corporate securities	1,000		—		(15)		—		985
Total	$	717,755	$	29,952	$	(269)	$	—	$	747,438

	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.

	June 30,				December 31,
	2020				2019
	Available-for-sale				Available-for-sale
	Amortized cost		Fair value		Amortized cost		Fair value
Due in one year or less	$	17,374	$	17,473	$	1,148	$	1,152
Due in one to five years	33,022		33,515		11,553		11,676
Due in five to ten years	30,203		31,373		18,287		18,887
Due in over ten years	197,313		210,471		158,616		165,990
	277,912		292,832		189,604		197,705
Mortgage-backed securities - residential	439,843		454,606		487,101		490,676
Total debt securities	$	717,755	$	747,438	$	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 June 30,				Six Months Ended June 30,
	2020		2019		2020		2019
Proceeds from sales	$	—	$	—	$	—	$	1,758
Proceeds from maturities, prepayments and calls	44,703		29,353		72,360		50,167
Gross realized gains	—		5		—		6
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 June 30, 2020 and December 31, 2019, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position:

	June 30, 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	$	14,746	$	(7)	$	—	$	—	$	14,746	$	(7)
Municipals, tax exempt	2,784		(247)		—		—		2,784		(247)
Corporate securities	985		(15)		—		—		985		(15)
Total	$	18,515	$	(269)	$	—	$	—	$	18,515	$	(269)

	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)
Total	$	63,074	$	(394)	$	175,730	$	(1,497)	$	238,804	$	(1,891)