Investment securities (Tables)

9 Months Ended

Sep. 30, 2019

Investments, Debt and Equity Securities [Abstract]

Summary of Amortized Cost of Securities and Fair Values

The amortized cost of securities and their fair values at September 30, 2019 and December 31, 2018 are shown below:

	September 30, 2019
	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair Value
Investment Securities
Available-for-sale debt securities
U.S. government agency securities	$	1,000	$	—	$	(1	)	$	999
Mortgage-backed securities - residential	481,580		5,784		(2,064		)	485,300
Municipals, tax exempt	165,100		8,754		(69		)	173,785
Treasury securities	7,415		17		—			7,432
Corporate securities	1,000		15		—			1,015
Total	$	656,095	$	14,570	$	(2,134	)	$	668,531

	December 31, 2018
	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair Value
Investment Securities
Available-for-sale debt securities
U.S. government agency securities	$	1,000	$	—	$	(11	)	$	989
Mortgage-backed securities - residential	520,654		1,191		(13,265		)	508,580
Municipals, tax exempt	138,994		1,565		(1,672		)	138,887
Treasury securities	7,385		—		(143		)	7,242
Total	$	668,033	$	2,756	$	(15,091	)	$	655,698

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.

	September 30, 2019				December 31, 2018
	Available-for-sale				Available-for-sale
	Amortized cost		Fair value		Amortized cost		Fair value
Due in one year or less	$	5,292	$	5,312	$	15,883	$	16,028
Due in one to five years	12,477		12,601		13,806		13,740
Due in five to ten years	15,412		15,978		18,539		18,387
Due in over ten years	141,334		149,340		99,151		98,963
	174,515		183,231		147,379		147,118
Mortgage-backed securities - residential	481,580		485,300		520,654		508,580
Total debt securities	$	656,095	$	668,531	$	668,033	$	655,698

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 September 30,				Nine Months Ended September 30,
	2019		2018		2019		2018
Proceeds from sales	$	22,740	$	—	$	24,498	$	221
Proceeds from maturities, prepayments and calls	28,694		20,068		78,861		54,576
Gross realized gains	1		—		7		1
Gross realized losses	76		—		83		9

Schedule of Gross Unrealized Losses

The following tables show gross unrealized losses at September 30, 2019 and December 31, 2018, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position:

	September 30, 2019
	Less than 12 months					12 months or more					Total
	Fair Value		Unrealized Loss			Fair Value		Unrealized Loss			Fair Value		Unrealized loss
U.S. government agency securities	$	—	$	—		$	999	$	(1	)	$	999	$	(1	)
Mortgage-backed securities - residential	26,610		(70		)	217,385		(1,994		)	243,995		(2,064		)
Municipals, tax exempt	10,553		(69		)	—		—			10,553		(69		)
Treasury securities	—		—			—		—			—		—
Total	$	37,163	$	(139	)	$	218,384	$	(1,995	)	$	255,547	$	(2,134	)

	December 31, 2018
	Less than 12 months					12 months or more					Total
	Fair Value		Unrealized Loss			Fair Value		Unrealized Loss			Fair Value		Unrealized loss
U.S. government agency securities	$	—	$	—		$	989	$	(11	)	$	989	$	(11	)
Mortgage-backed securities - residential	60,347		(478		)	335,769		(12,787		)	396,116		(13,265		)
Municipals, tax exempt	27,511		(366		)	25,343		(1,306		)	52,854		(1,672		)
Treasury securities	—		—			7,242		(143		)	7,242		(143		)
Total	$	87,858	$	(844	)	$	369,343	$	(14,247	)	$	457,201	$	(15,091	)