Investment Securities (Tables)

9 Months Ended

Sep. 30, 2019

Investment Securities

Schedule of amortized cost and fair value of securities

	September 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	$	29,653	$	85	$	—	$	29,738	$	389,470	$	—	$	—	$	389,470
Government agency debt securities		24,387		85		—		24,472		—		—		—		—
Government-sponsored enterprises debt securities		126,696		28		(75)		126,649		248,372		—		(6,778)		241,594
Government agency mortgage-backed securities		342,326		2,738		(1,159)		343,905		426,710		—		(15,174)		411,536
Government-sponsored enterprises mortgage-backed securities		366,346		6,831		(1,228)		371,949		156,056		85		(5,294)		150,847
Collateralized mortgage obligations:
Government agency		2,479,961		13,900		(7,337)		2,486,524		2,779,620		—		(97,171)		2,682,449
Government-sponsored enterprises		773,755		3,964		(3,874)		773,845		620,337		—		(17,745)		602,592
Debt securities issued by states and political subdivisions		—		—		—		—		19,854		—		—		19,854
Total available-for-sale securities	$	4,143,124	$	27,631	$	(13,673)	$	4,157,082	$	4,640,419	$	85	$	(142,162)	$	4,498,342

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

	September 30, 2019
	Amortized		Fair
(dollars in thousands)	Cost		Value
Due in one year or less	$	29,653	$	29,738
Due after one year through five years		126,696		126,649
Due after five years through ten years		—		—
Due after ten years		—		—
		156,349		156,387
Government agency debt securities		24,387		24,472
Government agency mortgage-backed securities		342,326		343,905
Government-sponsored enterprises mortgage-backed securities		366,346		371,949
Collateralized mortgage obligations:
Government agency		2,479,961		2,486,524
Government-sponsored enterprises		773,755		773,845
Total collateralized mortgage obligations		3,253,716		3,260,369
Total available-for-sale securities	$	4,143,124	$	4,157,082

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

	Time in Continuous Loss as of September 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	$	(75)	$	24,917	$	—	$	—	$	(75)	$	24,917
Government agency mortgage-backed securities		—		—		(1,159)		115,069		(1,159)		115,069
Government-sponsored enterprises mortgage-backed securities		—		—		(1,228)		115,456		(1,228)		115,456
Collateralized mortgage obligations:
Government agency		(820)		407,961		(6,517)		652,211		(7,337)		1,060,172
Government-sponsored enterprises		(161)		107,250		(3,713)		226,823		(3,874)		334,073
Total available-for-sale securities with unrealized losses	$	(1,056)	$	540,128	$	(12,617)	$	1,109,559	$	(13,673)	$	1,649,687

	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