Securities (Tables)

3 Months Ended

Mar. 31, 2021

Schedule Of Gain Loss On Investments Including Marketable Securities And Investments Held At Cost Income Statement Reported Amounts Summary [Line Items]

Amortized Cost and Fair Value of Debt Securities Available for Sale

	March 31, 2021								December 31, 2020
			Gross		Gross				Gross		Gross
Securities Available for Sale	Amortized		Unrealized		Unrealized		Fair		Amortized		Unrealized		Unrealized		Fair
(in thousands)	Cost		Gains		Losses		Value		Cost		Gains		Losses		Value
U.S. Treasury and government agency securities	$	219,343	$	2,703	$	4,554	$	217,492	$	207,365	$	6,289	$	284	$	213,370
Municipal obligations		308,298		13,757		5,393		316,662		309,342		17,536		153		326,725
Residential mortgage-backed securities		2,976,621		45,861		51,672		2,970,810		2,560,249		69,570		8		2,629,811
Commercial mortgage-backed securities		2,789,053		78,043		64,901		2,802,195		2,323,306		135,516		3,288		2,455,534
Collateralized mortgage obligations		305,078		6,835		—		311,913		354,472		7,651		—		362,123
Corporate debt securities		11,500		76		—		11,576		11,500		264		—		11,764
	$	6,609,893	$	147,275	$	126,520	$	6,630,648	$	5,766,234	$	236,826	$	3,733	$	5,999,327

Amortized Cost and Fair Value of Debt Securities Held to Maturity

	March 31, 2021								December 31, 2020
			Gross		Gross				Gross		Gross
Securities Held to Maturity	Amortized		Unrealized		Unrealized		Fair		Amortized		Unrealized		Unrealized		Fair
(in thousands)	Cost		Gains		Losses		Value		Cost		Gains		Losses		Value
U.S. Treasury and government agency securities	$	—	$	—	$	—	$	—	$	—	$	—	$	—	$	—
Municipal obligations		624,649		42,623		311		666,961		627,019		51,408		2		678,425
Residential mortgage-backed securities		53,298		1,315		459		54,154		21,951		1,469		—		23,420
Commercial mortgage-backed securities		574,923		35,164		1,041		609,046		549,686		54,587		—		604,273
Collateralized mortgage obligations		122,472		2,591		—		125,063		158,514		2,949		—		161,463
	$	1,375,342	$	81,693	$	1,811	$	1,455,224	$	1,357,170	$	110,413	$	2	$	1,467,581

Proceeds from Gross Gains on and Gross Losses on Sale of Securities

The following table presents the proceeds from, gross gain on, and gross losses on sales of securities during the three months ended March 31, 2021 and 2020.

	Three Months Ended March 31,
(in thousands)	2021		2020
Proceeds	$	—	$	124,122
Gross gains		—		1,082
Gross losses		—		970

Available for Sale Securities [Member]

Schedule Of Gain Loss On Investments Including Marketable Securities And Investments Held At Cost Income Statement Reported Amounts Summary [Line Items]

Amortized Cost and Fair Value of Debt Securities by Contractual Maturity

Debt Securities Available for Sale	Amortized		Fair
(in thousands)	Cost		Value
Due in one year or less	$	3,787	$	3,789
Due after one year through five years		259,889		278,591
Due after five years through ten years		2,861,768		2,875,550
Due after ten years		3,484,449		3,472,718
Total available for sale debt securities	$	6,609,893	$	6,630,648

Securities with Unrealized Losses

Available for Sale
March 31, 2021	Losses < 12 months				Losses 12 months or >				Total
(in thousands)	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
U.S. Treasury and government agency securities	$	125,672	$	4,554	$	—	$	—	$	125,672	$	4,554
Municipal obligations		66,344		5,393		—		—		66,344		5,393
Residential mortgage-backed securities		1,669,212		51,668		728		4		1,669,940		51,672
Commercial mortgage-backed securities		1,247,473		64,901		—		—		1,247,473		64,901
Collateralized mortgage obligations		—		—		—		—		—		—
Corporate debt securities		—		—		—		—		—		—
	$	3,108,701	$	126,516	$	728	$	4	$	3,109,429	$	126,520

Available for Sale
December 31, 2020	Losses < 12 months				Losses 12 months or >				Total
			Gross				Gross		Gross
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
(in thousands)	Value		Losses		Value		Losses		Value		Losses
U.S. Treasury and government agency securities	$	35,845		284	$	—	$	—	$	35,845	$	284
Municipal obligations		30,170		153		—		—		30,170		153
Residential mortgage-backed securities		530		2		760		6		1,290		8
Commercial mortgage-backed securities		446,190		3,288		—		—		446,190		3,288
Collateralized mortgage obligations		70		—		—		—		70		—
Corporate debt securities		2,000		—		—		—		2,000		—
	$	514,805	$	3,727	$	760	$	6	$	515,565	$	3,733

Held-to-maturity Securities [Member]

Schedule Of Gain Loss On Investments Including Marketable Securities And Investments Held At Cost Income Statement Reported Amounts Summary [Line Items]

Amortized Cost and Fair Value of Debt Securities by Contractual Maturity

Debt Securities Held to Maturity	Amortized		Fair
(in thousands)	Cost		Value
Due in one year or less	$	2,339	$	2,341
Due after one year through five years		225,806		239,613
Due after five years through ten years		662,066		704,949
Due after ten years		485,131		508,321
Total held to maturity securities	$	1,375,342	$	1,455,224

Securities with Unrealized Losses

Held to maturity
March 31, 2021	Losses < 12 months				Losses 12 months or >				Total
			Gross				Gross				Gross
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
(in thousands)	Value		Losses		Value		Losses		Value		Losses
U.S. Treasury and government agency securities	$	—	$	—	$	—	$	—	$	—	$	—
Municipal obligations		7,690		310		190		1		7,880		311
Residential mortgage-backed securities		33,123		459		—		—		33,123		459
Commercial mortgage-backed securities		37,033		1,041		—		—		37,033		1,041
Collateralized mortgage obligations		—		—		—		—		—		—
	$	77,846	$	1,810	$	190	$	1	$	78,036	$	1,811

Held to maturity
December 31, 2020	Losses < 12 months				Losses 12 months or >				Total
			Gross		Gross				Gross
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
(in thousands)	Value		Losses		Value		Losses		Value		Losses
U.S. Treasury and government agency securities	$	—	$	—	$	—	$	—	$	—	$	—
Municipal obligations		—		—		2,381		2		2,381		2
Residential mortgage-backed securities		—		—		—		—		—		—
Commercial mortgage-backed securities		—		—		—		—		—		—
Collateralized mortgage obligations		—		—		—		—		—		—
	$	—	$	—	$	2,381	$	2	$	2,381	$	2