Investment securities (Tables)

9 Months Ended

Sep. 30, 2021

Investments Debt And Equity Securities [Abstract]

Amortized Cost and Estimated Fair Value of Investment Securities

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

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
	(In thousands)
September 30, 2021
Investment securities available for sale:
U.S. Treasury and federal agencies	$	9,621	$	124	$	1	$	9,744
Mortgage-backed securities:
Government issued or guaranteed		3,328,080		147,942		543		3,475,479
Other debt securities		136,222		2,905		6,244		132,883
		3,473,923		150,971		6,788		3,618,106
Investment securities held to maturity:
U.S. Treasury and federal agencies		3,065		—		—		3,065
Obligations of states and political subdivisions		177		—		—		177
Mortgage-backed securities:
Government issued or guaranteed		2,288,934		63,523		6,312		2,346,145
Privately issued		64,929		10,901		13,901		61,929
Other debt securities		2,622		—		—		2,622
		2,359,727		74,424		20,213		2,413,938
Total debt securities	$	5,833,650	$	225,395	$	27,001	$	6,032,044
Equity and other securities:
Readily marketable equity — at fair value	$	80,016	$	3,341	$	901	$	82,456
Other — at cost		387,333		—		—		387,333
Total equity and other securities	$	467,349	$	3,341	$	901	$	469,789
December 31, 2020
Investment securities available for sale:
U.S. Treasury and federal agencies	$	9,154	$	198	$	14	$	9,338
Mortgage-backed securities:
Government issued or guaranteed		4,475,406		208,787		755		4,683,438
Privately issued		16		—		—		16
Other debt securities		136,451		1,664		8,301		129,814
		4,621,027		210,649		9,070		4,822,606
Investment securities held to maturity:
U.S. Treasury and federal agencies		2,999		—		—		2,999
Obligations of states and political subdivisions		1,531		9		—		1,540
Mortgage-backed securities:
Government issued or guaranteed		1,664,443		100,176		11		1,764,608
Privately issued		77,155		11,056		17,938		70,273
Other debt securities		2,861		—		—		2,861
		1,748,989		111,241		17,949		1,842,281
Total debt securities	$	6,370,016	$	321,890	$	27,019	$	6,664,887
Equity and other securities:
Readily marketable equity — at fair value	$	67,891	$	25,094	$	—	$	92,985
Other — at cost		381,117		—		—		381,117
Total equity and other securities	$	449,008	$	25,094	$	—	$	474,102

Amortized Cost and Estimated Fair Value of Debt Securities by Contractual Maturity

At September 30, 2021, the amortized cost and estimated fair value of debt securities by contractual maturity were as follows:

	Amortized Cost		Estimated Fair Value
	(In thousands)
Debt securities available for sale:
Due in one year or less	$	4,291		4,351
Due after one year through five years		13,974		14,616
Due after five years through ten years		97,578		98,981
Due after ten years		30,000		24,679
		145,843		142,627
Mortgage-backed securities available for sale		3,328,080		3,475,479
	$	3,473,923		3,618,106
Debt securities held to maturity:
Due in one year or less	$	176		177
Due after one year through five years		3,066		3,065
Due after ten years		2,622		2,622
		5,864		5,864
Mortgage-backed securities held to maturity		2,353,863		2,408,074
	$	2,359,727		2,413,938

Investment Securities in Continuous Unrealized Loss Position

A summary of investment securities that as of September 30, 2021 and December 31, 2020 had been in a continuous unrealized loss position for less than twelve months and those that had been in a continuous unrealized loss position for twelve months or longer follows:

	Less Than 12 Months					12 Months or More
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
	(In thousands)
September 30, 2021
Investment securities available for sale:
U.S. Treasury and federal agencies	$	1,424		(1	)		—		—
Mortgage-backed securities:
Government issued or guaranteed		981		(5	)		22,517		(538	)
Other debt securities		3,498		(37	)		64,437		(6,207	)
		5,903		(43	)		86,954		(6,745	)
Investment securities held to maturity:
Mortgage-backed securities:
Government issued or guaranteed		1,019,537		(6,301	)		1,400		(11	)
Privately issued		—		—			47,467		(13,901	)
		1,019,537		(6,301	)		48,867		(13,912	)
Total	$	1,025,440		(6,344	)		135,821		(20,657	)
December 31, 2020
Investment securities available for sale:
U.S. Treasury and federal agencies	$	985		(14	)		—		—
Mortgage-backed securities:
Government issued or guaranteed		18,687		(356	)		16,556		(399	)
Other debt securities		16,055		(181	)		63,462		(8,120	)
		35,727		(551	)		80,018		(8,519	)
Investment securities held to maturity:
Mortgage-backed securities:
Government issued or guaranteed		2,039		(11	)		—		—
Privately issued		—		—			52,418		(17,938	)
		2,039		(11	)		52,418		(17,938	)
Total	$	37,766		(562	)		132,436		(26,457	)