Investment securities (Tables)

6 Months Ended

Jun. 30, 2017

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 June 30, 2017 and December 31, 2016 are shown below:

	June 30, 2017
	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair Value
Securities Available-for-Sale
Debt securities
U.S. government agency securities	$	999	$	—	$	(9	)	$	990
Mortgage-backed securities - residential		416,011		679		(5,982	)		410,708
Municipals, tax exempt		119,960		3,617		(879	)		122,698
Treasury securities		10,325		—		(15	)		10,310
Total debt securities		547,295		4,296		(6,885	)		544,706
Equity securities		8,780		1		(130	)		8,651
Total securities available-for-sale	$	556,075	$	4,297	$	(7,015	)	$	553,357

	December 31, 2016
	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair Value
Securities Available-for-Sale
Debt securities
U.S. government agency securities	$	998	$	—	$	(13	)	$	985
Mortgage-backed securities - residential		450,874		939		(7,905	)		443,908
Municipals, tax exempt		116,034		3,003		(2,114	)		116,923
Treasury securities		11,809		—		(52	)		11,757
Total debt securities		579,715		3,942		(10,084	)		573,573
Equity securities		8,744		1		(135	)		8,610
Total securities available-for-sale	$	588,459	$	3,943	$	(10,219	)	$	582,183

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, 2017				December 31, 2016
	Available-for-sale				Available-for-sale
	Amortized cost		Fair value		Amortized cost		Fair value
Due in one year or less	$	7,798	$	7,870	$	9,290	$	9,352
Due in one to five years		32,299		33,470		25,520		26,340
Due in five to ten years		23,761		24,748		31,122		32,248
Due in over ten years		67,426		67,910		62,909		61,725
		131,284		133,998		128,841		129,665
Mortgage-backed securities - residential		416,011		410,708		450,874		443,908
	$	547,295	$	544,706	$	579,715	$	573,573

Summary of Sales of Available-for-Sale Securities

Sales of available-for-sale securities were as follows:

	Three Months Ended June 30,				Six Months Ended June 30,
	2017		2016		2017		2016
Proceeds from sales	$	12,158	$	166,732	$	12,158	$	268,995
Gross realized gains		77		2,939		77		4,339
Gross realized losses		48		348		48		348

Schedule of Gross Unrealized Losses

The following tables show gross unrealized losses at June 30, 2017 and December 31, 2016, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position:

	June 30, 2017
	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	$	990	$	9	$	—	$	—	$	990	$	9
Mortgage-backed securities - residential		366,265		5,402		17,527		580		383,792		5,982
Municipals, tax exempt		32,832		868		219		11		33,051		879
Treasury securities		10,310		15		—		—		10,310	$	15
Total debt securities		410,397		6,294		17,746		591		428,143		6,885
Equity securities		—		—		3,033		130		3,033		130
	$	410,397	$	6,294	$	20,779	$	721	$	431,176	$	7,015

	December 31, 2016
	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	$	985	$	13	$	—	$	—	$	985	$	13
Mortgage-backed securities - residential		390,595		7,230		19,073		675		409,668		7,905
Municipals, tax exempt		43,132		2,114		—		—		43,132		2,114
Treasury securities		10,256		52		—		—		10,256		52
Total debt securities		444,968		9,409		19,073		675		464,041		10,084
Equity securities		—		—		3,126		135		3,126		135
	$	444,968	$	9,409	$	22,199	$	810	$	467,167	$	10,219