Investment Securities (Tables)

12 Months Ended

Dec. 31, 2020

Investments, Debt and Equity Securities [Abstract]

Schedule of Available-for-sale Securities Reconciliation

The following table presents amortized cost, gross unrealized gains and losses, and fair values of securities available-for-sale as of the dates indicated:

	December 31,
	2020								2019
			Gross		Gross						Gross		Gross
	Amortized		Unrealized		Unrealized		Fair		Amortized		Unrealized		Unrealized		Fair
Security Type	Cost		Gains		Losses		Value		Cost		Gains		Losses		Value
	(In thousands)
Municipal securities	$	1,438,004	$	93,631	$	(18)	$	1,531,617	$	691,647	$	43,851	$	(339)	$	735,159
Agency commercial MBS	1,207,676		74,238		(37)		1,281,877		1,083,182		25,579		(537)		1,108,224
Agency residential CMOs	1,172,166		47,994		(280)		1,219,880		1,112,573		24,403		(579)		1,136,397
Agency residential MBS	329,488		12,483		(897)		341,074		294,606		10,593		(1)		305,198
Corporate debt securities	308,803		3,490		(404)		311,889		17,000		3,748		—		20,748
Asset-backed securities	248,739		1,534		(770)		249,503		216,133		320		(1,670)		214,783
Collateralized loan obligations	136,777		23		(924)		135,876		124,134		25		(403)		123,756
Private label residential CMOs	110,891		6,076		(21)		116,946		96,066		3,430		(13)		99,483
SBA securities	39,437		2,217		(27)		41,627		47,765		506		(13)		48,258
U.S. Treasury securities	4,989		313		—		5,302		4,985		196		—		5,181
Total	$	4,996,970	$	241,999	$	(3,378)	$	5,235,591	$	3,688,091	$	112,651	$	(3,555)	$	3,797,187

Schedule of Realized Gain (Loss)

The following table presents the amortized cost of securities sold with related gross realized gains, gross realized losses, and net realized gains for the years indicated:

	Year Ended December 31,
Sales of Securities Available-for-Sale	2020		2019		2018
	(In thousands)
Amortized cost of securities sold	$	160,254	$	1,559,415	$	563,624
Gross realized gains	$	13,222	$	29,584	$	9,225
Gross realized losses	(51)		(4,139)		(1,049)
Net realized gains	$	13,171	$	25,445	$	8,176

Unrealized losses on investment securities

Unrealized Losses on Securities Available-for-Sale

The following tables present the gross unrealized losses and fair values of securities available-for-sale that were in unrealized loss positions as of the dates indicated:

	December 31, 2020
	Less Than 12 Months				12 Months or More				Total
			Gross				Gross				Gross
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
Security Type	Value		Losses		Value		Losses		Value		Losses
	(In thousands)
Municipal securities	$	5,919	$	(18)	$	—	$	—	$	5,919	$	(18)
Agency commercial MBS	58,408		(37)		—		—		58,408		(37)
Agency residential CMOs	97,863		(280)		—		—		97,863		(280)
Agency residential MBS	90,722		(897)		—		—		90,722		(897)
Corporate debt securities	87,596		(404)		—		—		87,596		(404)
Asset-backed securities	17,694		(63)		61,031		(707)		78,725		(770)
Collateralized loan obligations	96,442		(729)		28,972		(195)		125,414		(924)
Private label residential CMOs	788		(19)		74		(2)		862		(21)
SBA securities	2,127		(27)		—		—		2,127		(27)
Total	$	457,559	$	(2,474)	$	90,077	$	(904)	$	547,636	$	(3,378)

	December 31, 2019
	Less Than 12 Months				12 Months or More				Total
			Gross				Gross				Gross
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
Security Type	Value		Losses		Value		Losses		Value		Losses
	(In thousands)
Municipal securities	$	38,667	$	(339)	$	—	$	—	$	38,667	$	(339)
Agency commercial MBS	214,862		(537)		—		—		214,862		(537)
Agency residential CMOs	180,071		(572)		1,456		(7)		181,527		(579)
Agency residential MBS	—		—		186		(1)		186		(1)
Asset-backed securities	165,575		(1,670)		—		—		165,575		(1,670)
Collateralized loan obligations	102,469		(403)		—		—		102,469		(403)
Private label residential CMOs	9,872		(11)		114		(2)		9,986		(13)
SBA securities	4,565		(13)		—		—		4,565		(13)
Total	$	716,081	$	(3,545)	$	1,756	$	(10)	$	717,837	$	(3,555)

Investments Classified by Contractual Maturity Date

The following table presents the contractual maturities of our available-for-sale securities portfolio based on amortized cost and carrying value as of the date indicated.

	December 31, 2020
	Amortized		Fair
Maturity	Cost		Value
	(In thousands)
Due in one year or less	$	6,063	$	6,091
Due after one year through five years	575,561		606,388
Due after five years through ten years	1,306,179		1,368,746
Due after ten years	3,109,167		3,254,366
Total securities available-for-sale	$	4,996,970	$	5,235,591

Investment Income

The following table presents the composition of our interest income on investment securities for the years indicated:

	Year Ended December 31,
	2020		2019		2018
	(In thousands)
Taxable interest	$	80,426	$	85,968	$	68,504
Non-taxable interest	24,771		27,955		41,376
Dividend income	1,573		1,646		1,739
Total interest income on investment securities	$	106,770	$	115,569	$	111,619