Investment Securities (Tables)

6 Months Ended

Jun. 30, 2019

Schedule of amortized cost and fair value of securities

	June 30, 2019								December 31, 2018
	Amortized		Unrealized		Unrealized		Fair		Amortized		Unrealized		Unrealized		Fair
(dollars in thousands)	Cost		Gains		Losses		Value		Cost		Gains		Losses		Value
U.S. Treasury securities	$	29,477	$	79	$	—	$	29,556	$	389,470	$	—	$	—	$	389,470
Government agency debt securities		24,583		130		—		24,713		—		—		—		—
Government-sponsored enterprises debt securities		164,719		1		(404)		164,316		248,372		—		(6,778)		241,594
Government agency mortgage-backed securities		363,295		2,043		(3,117)		362,221		426,710		—		(15,174)		411,536
Government-sponsored enterprises mortgage-backed securities		152,506		852		(1,675)		151,683		156,056		85		(5,294)		150,847
Collateralized mortgage obligations:
Government agency		2,619,502		9,107		(15,144)		2,613,465		2,779,620		—		(97,171)		2,682,449
Government-sponsored enterprises		1,045,515		8,549		(4,542)		1,049,522		620,337		—		(17,745)		602,592
Debt securities issued by states and political subdivisions		—		—		—		—		19,854		—		—		19,854
Total available-for-sale securities	$	4,399,597	$	20,761	$	(24,882)	$	4,395,476	$	4,640,419	$	85	$	(142,162)	$	4,498,342

Schedule of amortized cost and fair value of debt securities by contractual maturity

	June 30, 2019
	Amortized		Fair
(dollars in thousands)	Cost		Value
Due in one year or less	$	29,477	$	29,556
Due after one year through five years		99,992		99,701
Due after five years through ten years		64,727		64,615
Due after ten years		—		—
		194,196		193,872
Government agency debt securities		24,583		24,713
Government agency mortgage-backed securities		363,295		362,221
Government-sponsored enterprises mortgage-backed securities		152,506		151,683
Collateralized mortgage obligations:
Government agency		2,619,502		2,613,465
Government-sponsored enterprises		1,045,515		1,049,522
Total collateralized mortgage obligations		3,665,017		3,662,987
Total available-for-sale securities	$	4,399,597	$	4,395,476

Schedule of gross unrealized losses and fair values of securities in a continuous loss position

	Time in Continuous Loss as of June 30, 2019
	Less Than 12 Months				12 Months or More				Total
	Unrealized				Unrealized				Unrealized
(dollars in thousands)	Losses		Fair Value		Losses		Fair Value		Losses		Fair Value
Government-sponsored enterprises debt securities	$	—	$	—	$	(404)	$	76,290	$	(404)	$	76,290
Government agency mortgage-backed securities		—		—		(3,117)		154,670		(3,117)		154,670
Government-sponsored enterprises mortgage-backed securities		—		—		(1,675)		120,791		(1,675)		120,791
Collateralized mortgage obligations:
Government agency		(181)		76,844		(14,963)		1,407,580		(15,144)		1,484,424
Government-sponsored enterprises		(143)		138,443		(4,399)		271,124		(4,542)		409,567
Total available-for-sale securities with unrealized losses	$	(324)	$	215,287	$	(24,558)	$	2,030,455	$	(24,882)	$	2,245,742

	Time in Continuous Loss as of December 31, 2018
	Less Than 12 Months				12 Months or More				Total
	Unrealized				Unrealized				Unrealized
(dollars in thousands)	Losses		Fair Value		Losses		Fair Value		Losses		Fair Value
Government-sponsored enterprises debt securities	$	—	$	—	$	(6,778)	$	157,939	$	(6,778)	$	157,939
Government agency mortgage-backed securities		—		—		(15,174)		373,891		(15,174)		373,891
Government-sponsored enterprises mortgage-backed securities		(1)		172		(5,293)		125,869		(5,294)		126,041
Collateralized mortgage obligations:
Government agency		—		—		(97,171)		2,475,532		(97,171)		2,475,532
Government-sponsored enterprises		—		—		(17,745)		486,175		(17,745)		486,175
Total available-for-sale securities with unrealized losses	$	(1)	$	172	$	(142,161)	$	3,619,406	$	(142,162)	$	3,619,578