Investment Securities Available-for-Sale (Tables)

3 Months Ended

Mar. 31, 2018

Investments, Debt and Equity Securities [Abstract]

Schedule of available-for-sale securities reconciliation

Amortized cost and estimated fair value of securities available-for-sale are summarized as follows:

			Gross			Gross		Estimated
March 31, 2018	Amortized		Unrealized			Unrealized		Fair
(dollars in thousands)	Cost		Gains			Losses		Value
U. S. agency securities	$	196,210	$	130	#	$	4,249	$	192,091
Residential mortgage backed securities		337,362		113			8,235		329,240
Municipal bonds		48,577		642			614		48,605
Corporate bonds		8,004		159			—		8,163
Other equity investments		218		—			—		218
	$	590,371	$	1,044		$	13,098	$	578,317

			Gross			Gross		Estimated
December 31, 2017	Amortized		Unrealized			Unrealized		Fair
(dollars in thousands)	Cost		Gains			Losses		Value
U. S. agency securities	$	198,115	$	283	#	$	2,414	$	195,984
Residential mortgage backed securities		322,067		187			4,418		317,836
Municipal bonds		60,976		1,295			214		62,057
Corporate bonds		13,010		163			—		13,173
Other equity investments		218		—			—		218
	$	594,386	$	1,928		$	7,046	$	589,268

Schedule of unrealized loss on investments

Gross unrealized losses and fair value by length of time that the individual available-for-sale securities have been in a continuous unrealized loss position are as follows:

			Less than				12 Months
			12 Months				or Greater				Total
			Estimated				Estimated				Estimated
March 31, 2018	Number of		Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
(dollars in thousands)	Securities		Value		Losses		Value		Losses		Value		Losses
U. S. agency securities		44	$	113,476	$	2,469	$	54,634	$	1,780	$	168,110	$	4,249
Residential mortgage backed securities		148		159,464		3,326		146,174		4,909		305,638		8,235
Municipal bonds		13		23,180		614		—		—		23,180		614
		205	$	296,120	$	6,409	$	200,808	$	6,689	$	496,928	$	13,098

			Less than				12 Months
			12 Months				or Greater				Total
			Estimated				Estimated				Estimated
December 31, 2017	Number of		Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
(dollars in thousands)	Securities		Value		Losses		Value		Losses		Value		Losses
U. S. agency securities		38	$	102,264	$	1,073	$	55,093	$	1,341	$	157,357	$	2,414
Residential mortgage backed securities		137		152,350		1,306		147,953		3,112		300,303		4,418
Municipal bonds		8		17,446		214		—		—		17,446		214
		183	$	272,060	$	2,593	$	203,046	$	4,453	$	475,106	$	7,046

Schedule of available-for-sale securities by contractual maturity

The amortized cost and estimated fair value of investments available-for-sale at March 31, 2018 and December 31, 2017 by contractual maturity are shown in the table below. Expected maturities for residential mortgage backed securities will differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties.

	March 31, 2018				December 31, 2017
	Amortized		Estimated		Amortized		Estimated
(dollars in thousands)	Cost		Fair Value		Cost		Fair Value
U. S. agency securities maturing:
One year or less	$	111,940	$	108,886	$	109,893	$	108,198
After one year through five years		70,523		69,917		74,106		73,916
Five years through ten years		13,747		13,288		14,116		13,870
Residential mortgage backed securities		337,362		329,240		322,067		317,836
Municipal bonds maturing:
One year or less		5,078		5,139		5,068		5,171
After one year through five years		19,366		19,654		19,405		19,879
Five years through ten years		23,064		22,686		35,432		35,846
After ten years		1,069		1,126		1,071		1,161
Corporate bonds maturing:
After one year through five years		6,504		6,663		11,510		11,673
After ten years		1,500		1,500		1,500		1,500
Other equity investments		218		218		218		218
	$	590,371	$	578,317	$	594,386	$	589,268