Investment Securities (Tables)

3 Months Ended

Mar. 31, 2019

Investment Securities

Schedule of amortized cost and fair value of securities

	March 31, 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	$	—	$	—	$	—	$	—	$	389,470	$	—	$	—	$	389,470
Government agency debt securities		24,778		—		(13)		24,765		—		—		—		—
Government-sponsored enterprises debt securities		164,718		—		(3,123)		161,595		248,372		—		(6,778)		241,594
Government agency mortgage-backed securities		377,960		—		(6,925)		371,035		426,710		—		(15,174)		411,536
Government-sponsored enterprises mortgage-backed securities		131,884		71		(4,059)		127,896		156,056		85		(5,294)		150,847
Collateralized mortgage obligations:
Government agency		2,778,862		1,404		(50,100)		2,730,166		2,779,620		—		(97,171)		2,682,449
Government-sponsored enterprises		1,076,399		4,607		(10,803)		1,070,203		620,337		—		(17,745)		602,592
Debt securities issued by states and political subdivisions		—		—		—		—		19,854		—		—		19,854
Total available-for-sale securities	$	4,554,601	$	6,082	$	(75,023)	$	4,485,660	$	4,640,419	$	85	$	(142,162)	$	4,498,342

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

	March 31, 2019
	Amortized		Fair
(dollars in thousands)	Cost		Value
Due in one year or less	$	—	$	—
Due after one year through five years		99,992		98,193
Due after five years through ten years		64,726		63,402
Due after ten years		—		—
		164,718		161,595
Government agency debt securities		24,778		24,765
Government agency mortgage-backed securities		377,960		371,035
Government-sponsored enterprises mortgage-backed securities		131,884		127,896
Collateralized mortgage obligations:
Government agency		2,778,862		2,730,166
Government-sponsored enterprises		1,076,399		1,070,203
Total mortgage-backed securities and collateralized mortgage obligations		4,389,883		4,324,065
Total available-for-sale securities	$	4,554,601	$	4,485,660

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

	Time in Continuous Loss as of March 31, 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 agency debt securities	$	(13)	$	24,765	$	—	$	—	$	(13)	$	24,765
Government-sponsored enterprises debt securities		—		—		(3,123)		161,595		(3,123)		161,595
Government agency mortgage-backed securities		—		—		(6,925)		371,035		(6,925)		371,035
Government-sponsored enterprises mortgage-backed securities		—		—		(4,059)		123,430		(4,059)		123,430
Collateralized mortgage obligations:
Government agency		(327)		99,455		(49,773)		2,417,727		(50,100)		2,517,182
Government-sponsored enterprises		(450)		138,465		(10,353)		449,284		(10,803)		587,749
Total available-for-sale securities with unrealized losses	$	(790)	$	262,685	$	(74,233)	$	3,523,071	$	(75,023)	$	3,785,756

	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