Investment Securities (Tables)

9 Months Ended

Sep. 30, 2021

Investment Securities

Schedule of amortized cost and fair value of securities

	September 30, 2021								December 31, 2020
	Amortized		Unrealized		Unrealized		Fair		Amortized		Unrealized		Unrealized		Fair
(dollars in thousands)	Cost		Gains		Losses		Value		Cost		Gains		Losses		Value
U.S. Treasury and government agency debt securities	$	188,861	$	552	$	(1,552)	$	187,861	$	170,123	$	1,359	$	(61)	$	171,421
Mortgage-backed securities:
Residential - Government agency		95,337		2,797		—		98,134		155,169		5,293		—		160,462
Residential - Government-sponsored enterprises		1,455,375		9,944		(6,441)		1,458,878		434,282		13,643		(725)		447,200
Commercial - Government agency		449,147		4,653		(5,206)		448,594		583,232		16,537		(119)		599,650
Commercial - Government-sponsored enterprises		1,337,925		4,008		(40,684)		1,301,249		931,095		9,045		(7,983)		932,157
Collateralized mortgage obligations:
Government agency		2,053,171		16,316		(9,623)		2,059,864		1,902,326		32,246		(1,019)		1,933,553
Government-sponsored enterprises		2,414,450		7,506		(22,809)		2,399,147		1,808,804		18,991		(823)		1,826,972
Total available-for-sale securities	$	7,994,266	$	45,776	$	(86,315)	$	7,953,727	$	5,985,031	$	97,114	$	(10,730)	$	6,071,415

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

	September 30, 2021
	Amortized		Fair
(dollars in thousands)	Cost		Value
Due in one year or less	$	—	$	—
Due after one year through five years		41,481		41,777
Due after five years through ten years		83,227		82,733
Due after ten years		64,153		63,351
		188,861		187,861
Mortgage-backed securities:
Residential - Government agency		95,337		98,134
Residential - Government-sponsored enterprises		1,455,375		1,458,878
Commercial - Government agency		449,147		448,594
Commercial - Government-sponsored enterprises		1,337,925		1,301,249
Total mortgage-backed securities		3,337,784		3,306,855
Collateralized mortgage obligations:
Government agency		2,053,171		2,059,864
Government-sponsored enterprises		2,414,450		2,399,147
Total collateralized mortgage obligations		4,467,621		4,459,011
Total available-for-sale securities	$	7,994,266	$	7,953,727

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

	Time in Continuous Loss as of September 30, 2021
	Less Than 12 Months				12 Months or More				Total
	Unrealized				Unrealized				Unrealized
(dollars in thousands)	Losses		Fair Value		Losses		Fair Value		Losses		Fair Value
U.S. Treasury and government agency debt securities	$	(1,552)	$	128,093	$	—	$	—	$	(1,552)	$	128,093
Mortgage-backed securities:
Residential - Government-sponsored enterprises		(5,799)		818,313		(642)		20,693		(6,441)		839,006
Commercial - Government agency		(4,960)		230,013		(246)		6,901		(5,206)		236,914
Commercial - Government-sponsored enterprises		(27,869)		874,759		(12,815)		159,985		(40,684)		1,034,744
Collateralized mortgage obligations:
Government agency		(9,623)		936,557		—		—		(9,623)		936,557
Government-sponsored enterprises		(22,809)		1,611,979		—		—		(22,809)		1,611,979
Total available-for-sale securities with unrealized losses	$	(72,612)	$	4,599,714	$	(13,703)	$	187,579	$	(86,315)	$	4,787,293

	Time in Continuous Loss as of December 31, 2020
	Less Than 12 Months				12 Months or More				Total
	Unrealized				Unrealized				Unrealized
(dollars in thousands)	Losses		Fair Value		Losses		Fair Value		Losses		Fair Value
U.S. Treasury and government agency debt securities	$	(61)	$	38,507	$	—	$	—	$	(61)	$	38,507
Mortgage-backed securities:
Residential - Government-sponsored enterprises		(725)		64,987		—		—		(725)		64,987
Commercial - Government agency		(119)		32,346		—		—		(119)		32,346
Commercial - Government-sponsored enterprises		(7,983)		427,759		—		—		(7,983)		427,759
Collateralized mortgage obligations:
Government agency		(994)		209,124		(25)		6,190		(1,019)		215,314
Government-sponsored enterprises		(823)		296,160		—		—		(823)		296,160
Total available-for-sale securities with unrealized losses	$	(10,705)	$	1,068,883	$	(25)	$	6,190	$	(10,730)	$	1,075,073