Investment Securities (Tables)

9 Months Ended

Sep. 30, 2020

Investments, Debt and Equity Securities [Abstract]

The amortized cost and fair value of investment securities were as follows:



	Investment Securities Available-for-sale, At Fair Value
(In thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
At September 30, 2020
Debt securities:
Obligations of states and political subdivisions	$	836,691	$	41,081	$	1,008	$	876,764
Government and government-sponsored enterprises	205,213		372		500		205,085
Mortgage-backed securities:
Residential agency	5,229,551		171,039		580		5,400,010
Residential non-agency	205,029		4,571		3		209,597
Commercial agency	671,387		40,373		180		711,580
Commercial non-agency	39,368		3,295		—		42,663
Total mortgage-backed debt securities	6,145,335		219,278		763		6,363,850
Corporate debt and trust preferred securities	453		11		—		464
Total investment securities available-for-sale	$	7,187,692	$	260,742	$	2,271	$	7,446,163
At December 31, 2019
Debt securities:
Obligations of states and political subdivisions	$	852,096	$	12,446	$	687	$	863,855
Government and government-sponsored enterprises	235,045		18		678		234,385
Mortgage-backed securities:
Residential agency	4,492,427		68,797		6,103		4,555,121
Residential non-agency	374,046		1,166		616		374,596
Commercial agency	645,814		8,639		2,049		652,404
Commercial non-agency	39,398		17		205		39,210
Total mortgage-backed debt securities	5,551,685		78,619		8,973		5,621,331
Corporate debt and trust preferred securities	451		—		21		430
Total investment securities available-for-sale	$	6,639,277	$	91,083	$	10,359	$	6,720,001



	Investment Securities Held-to-Maturity
(In thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
At September 30, 2020
Residential agency mortgage-backed securities	$	166,594	$	10,262	$	207	$	176,649
Corporate debt and trust preferred securities	3,715		—		—		3,715
Total investment securities held-to-maturity ⁽¹⁾	$	170,309	$	10,262	$	207	$	180,364
At December 31, 2019
Residential agency mortgage-backed securities	$	135,769	$	5,576	$	177	$	141,168
Corporate debt and trust preferred securities	3,676		—		—		3,676
Total investment securities held-to-maturity	$	139,445	$	5,576	$	177	$	144,844


(1)	The adoption of CECL was inconsequential to held-to-maturity investment securities. At September 30, 2020 there was no ACL for investment securities held-to-maturity.

Schedule of Gross Unrealized Losses and Fair Value of Debt Securities Available for Sale and Debt Securities Held to Maturity that are in a Loss Position

Gross unrealized losses and fair value of available-for-sale investment securities aggregated by investment category and the length of time the securities were in a continuous loss position were as follows:



	At September 30, 2020
	Less than 12 months				12 months or more				Total
(In thousands)	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
Investment securities available-for-sale
Debt securities:
Obligations of states and political subdivisions	$	47,548	$	1,008	$	—	$	—	$	47,548	$	1,008
Government and government sponsored enterprises	100,992		500		—		—		100,992		500
Mortgage-backed securities:
Residential agency	177,611		580		—		—		177,611		580
Residential non-agency	3,691		3		—		—		3,691		3
Commercial agency	58,349		180		—		—		58,349		180
Commercial non-agency	—		—		—		—		—		—
Total mortgage-backed debt securities	239,651		763		—		—		239,651		763
Total investment securities available-for-sale	$	388,191	$	2,271	$	—	$	—	$	388,191	$	2,271
Investment securities held-to-maturity
Residential agency mortgage-backed securities	51,766		207		—		—		51,766		207
Total investment securities held-to-maturity	$	51,766	$	207	$	—	$	—	$	51,766	$	207



	At December 31, 2019
	Less than 12 months				12 months or more				Total
(In thousands)	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
Investment securities available-for-sale
Debt securities:
Obligations of states and political subdivisions	$	60,639	$	687	$	—	$	—	$	60,639	$	687
Government and government sponsored enterprises	226,177		678		—		—		226,177		678
Mortgage-backed securities:
Residential agency	667,511		3,586		200,534		2,517		868,045		6,103
Residential non-agency	140,403		616		—		—		140,403		616
Commercial agency	176,880		2,049		—		—		176,880		2,049
Commercial non-agency	25,560		205		—		—		25,560		205
Total mortgage-backed debt securities	1,010,354		6,456		200,534		2,517		1,210,888		8,973
Corporate debt and trust preferred securities	430		21		—		—		430		21
Total investment securities available-for-sale	$	1,297,600	$	7,842	$	200,534	$	2,517	$	1,498,134	$	10,359

Realized Gain (Loss) on Investments

The gross gains and losses on sales of investment securities were as follows:



	Three Months Ended September 30,				Nine Months Ended September 30,
(In thousands)	2020		2019		2020		2019
Gross realized gains	$	2,309	$	7,717	$	2,309	$	10,872
Gross realized losses	—		1,849		—		3,491
Recoveries on previously impaired investment securities held-to-maturity	15		32		23		36
Net gains on investment securities	$	2,324	$	5,900	$	2,332	$	7,417

Schedule of Amortized Cost and Fair Value of Debt Securities Available for Sale and Debt Securities Held to Maturity by Contractual Maturity

The amortized cost and fair value of investment securities by final contractual maturity were as follows. Securities with multiple maturity dates are classified in the period of final maturity. The final contractual maturities do not consider possible prepayments and therefore expected maturities may differ because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties.



	At September 30, 2020				At December 31, 2019
(In thousands)	Amortized Cost		Fair Value		Amortized Cost		Fair Value
Investment Securities Available-for-Sale
Due in one year or less	$	45,229	$	45,518	$	66,124	$	66,112
Due in 1-5 years	171,134		176,145		191,364		192,065
Due in 5-10 years	664,743		703,227		547,813		555,523
Due after 10 years	6,306,586		6,521,273		5,833,976		5,906,301
Total investment securities available-for-sale	$	7,187,692	$	7,446,163	$	6,639,277	$	6,720,001
Investment Securities Held-to-Maturity
Due in one year or less	$	400	$	400	$	—	$	—
Due in 1-5 years	$	3,150	$	3,150	$	3,550	$	3,550
Due in 5-10 years	49		55		58		64
Due after 10 years	166,710		176,759		135,837		141,230
Total investment securities held-to-maturity	$	170,309	$	180,364	$	139,445	$	144,844