Investment securities (Tables)

9 Months Ended

Sep. 30, 2016

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, 2016 and December 31, 2015 are shown below (in thousands):

	September 30, 2016
	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair Value
Securities Available-for-Sale
Debt securities
U.S. government agency securities	$	2,501	$	—	$	—		$	2,501
Mortgage-backed securities - residential		429,156		4,678		(270	)		433,564
Municipals, tax exempt		99,171		4,987		(46	)		104,112
Treasury securities		4,504		2		—			4,506
Total debt securities		535,332		9,667		(316	)		544,683
Equity securities		8,722		26		(74	)		8,674
Total securities available-for-sale	$	544,054	$	9,693	$	(390	)	$	553,357

	December 31, 2015
	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair Value
Securities Available-for-Sale
Debt securities
U.S. government agency securities	$	34,161	$	—	$	(353	)	$	33,808
Mortgage-backed securities - residential		524,141		3,675		(5,443	)		522,373
Municipals, tax exempt		74,945		4,892		—			79,837
Treasury securities		4,507		—		(22	)		4,485
Total debt securities		637,754		8,567		(5,818	)		640,503
Equity securities		8,971	3			(90	)		8,884
Total securities available-for-sale	$	646,725	$	8,570	$	(5,908	)	$	649,387

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, 2016				December 31, 2015
	Available-for-sale				Available-for-sale
	Amortized cost		Fair value		Amortized cost		Fair value
Due in one year or less	$	5,203	$	5,206	$	6,849	$	6,886
Due in one to five		7,486		7,608		44,108		44,358
Due in five to ten years		37,340		39,790		29,964		31,927
Due in over ten years		56,147		58,515		32,692		34,959
		106,176		111,119		113,613		118,130
Mortgage-backed securities - residential		429,156		433,564		524,141		522,373
	$	535,332	$	544,683	$	637,754	$	640,503

Summary of Sales of Available-for-Sale Securities

Sales of available-for-sale securities were as follows (in thousands):

	Three Months Ended September 30,				Nine Months Ended September 30,
	2016		2015		2016		2015
Proceeds from sales	$	1,668	$	157,475	$	270,663	$	268,830
Gross realized gains		416		47		4,755		1,842
Gross realized losses		—		—		348		—

Schedule of Gross Unrealized Losses

The following tables show gross unrealized losses at September 30, 2016 and December 31, 2015, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position (in thousands):

	September 30, 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	$	—	$	—	$	—	$	—	$	—	$	—
Mortgage-backed securities - residential		35,601		96		20,373		174		55,974		270
Municipals, tax exempt		4,286		46		—		—		4,286		46
Treasury securities		—		—		—		—		—		—
Total debt securities		39,887		142		20,373		174		60,260		316
Equity securities		—		—		1,543		74		1,543		74
	$	39,887	$	142	$	21,916	$	248	$	61,803	$	390

	December 31, 2015
	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	$	15,887	$	124	$	17,921	$	229	$	33,808	$	353
Mortgage-backed securities - residential		219,756		1,778		121,362		3,665		341,118		5,443
Municipals, tax exempt		4,485		22		—		—		4,485		22
Total debt securities		240,128		1,924		139,283		3,894		379,411		5,818
Equity securities		—		—		1,583		90		1,583		90
	$	240,128	$	1,924	$	140,866	$	3,984	$	380,994	$	5,908