Securities Available for Sale (Tables)

12 Months Ended

Dec. 31, 2018

Available-for-sale Securities [Abstract]

Summary of Securities Available for Sale

The following is a summary of securities available for sale at December 31, 2018 and 2017:



	December 31, 2018
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
	(Dollars in thousands)
Debt securities:
U.S. Government agency and U.S. Government sponsored enterprises:
Collateralized mortgage obligations	$	914,710	$	1,541	$	(21,129	)	$	895,122
Mortgage-backed securities:
Residential	415,659		47		(13,101		)	402,605
Commercial	481,081		1,024		(12,979		)	469,126
Corporate securities	5,000		—		(1,174		)	3,826
Municipal securities	77,168		398		(1,980		)	75,586
Total investment securities available for sale	$	1,893,618	$	3,010	$	(50,363	)	$	1,846,265


	December 31, 2017
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
	(Dollars in thousands)
Debt securities:
U.S. Government agency and U.S. Government sponsored enterprises:
Collateralized mortgage obligations	$	856,193	$	58	(17,542		)	$	838,709
Mortgage-backed securities:
Residential	477,676		521		(6,983		)	471,214
Commercial	308,046		—		(6,681		)	301,365
Corporate securities	4,997		—		(522		)	4,475
Municipal securities	82,542		870		(875		)	82,537
Total debt securities	1,729,454		1,449		(32,603		)	1,698,300
Mutual funds	22,425		17		(485		)	21,957
Total investment securities available for sale	$	1,751,879	$	1,466	$	(33,088	)	$	1,720,257

Schedule of Realized Gain (Loss)

The proceeds from sales of securities and total gains and losses are listed below:



	Year ended December 31,
	2018		2017			2016
	(Dollars in thousands)
Proceeds from investments sold	$	—	$	128,791		$	217,079

Gains from sales of securities	—		402			1,032
Losses from sales of securities	—		(101		)	(84		)
Gains from called securities	—		—			2
Net gain on sales or called securities	$	—	$	301		$	950

Investments Classified by Contractual Maturity Date

The amortized cost and estimated fair value of securities at December 31, 2018, by contractual maturity, are shown below. Expected maturities may differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties. Securities not due at a single maturity date are shown separately.



	December 31, 2018
	Amortized Cost		Estimated Fair Value
	(Dollars in thousands)
Available for sale:
Due within one year	$	751	$	761
Due after one year through five years	17,565		17,669
Due after five years through ten years	27,873		27,901
Due after ten years	35,979		33,081
U.S. Government agency and U.S. Government sponsored enterprises
Collateralized mortgage obligations	914,710		895,122
Mortgage-backed securities:
Residential	415,659		402,605
Commercial	481,081		469,126
Total	$	1,893,618	$	1,846,265

Schedule of Unrealized Loss on Investments



	December 31, 2018
	Less than 12 months						12 months or longer						Total
Description of Securities	Number of Securities	Fair Value		Gross Unrealized Losses			Number of Securities	Fair Value		Gross Unrealized Losses			Number of Securities	Fair Value		Gross Unrealized Losses
	(Dollars in thousands)
Collateralized mortgage obligations*	1	$	8,041	$	(28	)	93	$	700,095	$	(21,101	)	94	$	708,136	$	(21,129	)
Mortgage-backed securities:
Residential*	4	19,973		(37		)	45	363,334		(13,064		)	49	383,307		(13,101		)
Commercial*	3	38,494		(218		)	27	312,428		(12,761		)	30	350,922		(12,979		)
Corporate securities	—	—		—			1	3,826		(1,174		)	1	3,826		(1,174		)
Municipal securities	13	5,528		(83		)	32	42,444		(1,897		)	45	47,972		(1,980		)
Total	21	$	72,036	$	(366	)	198	$	1,422,127	$	(49,997	)	219	$	1,494,163	$	(50,363	)



	December 31, 2017
	Less than 12 months						12 months or longer						Total
Description of Securities	Number of Securities	Fair Value		Gross Unrealized Losses			Number of Securities	Fair Value		Gross Unrealized Losses			Number of Securities	Fair Value		Gross Unrealized Losses
	(Dollars in thousands)
Collateralized mortgage obligations*	38	$	425,198	$	(5,954	)	53	$	408,526	$	(11,588	)	91	$	833,724	$	(17,542	)
Mortgage-backed securities:
Residential*	20	195,086		(1,282		)	23	230,616		(5,701		)	43	425,702		(6,983		)
Commercial*	16	186,357		(1,614		)	8	115,008		(5,067		)	24	301,365		(6,681		)
Corporate securities	1	4,475		(522		)	—	—		—			1	4,475		(522		)
Municipal securities	18	9,295		(69		)	3	22,144		(806		)	21	31,439		(875		)
Mutual funds	1	8,899		(101		)	3	11,579		(384		)	4	20,478		(485		)
Total	94	$	829,310	$	(9,542	)	90	$	787,873	$	(23,546	)	184	$	1,617,183	$	(33,088	)