Investment securities (Tables)

6 Months Ended

Jun. 30, 2019

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)
June 30, 2019
Investment securities available for sale:
U.S. Treasury and federal agencies	$	431,334	$	17	$	1,538	$	429,813
Obligations of states and political subdivisions		1,015		3		3		1,015
Mortgage-backed securities:
Government issued or guaranteed		6,789,309		66,806		37,782		6,818,333
Privately issued		16		—		—		16
Other debt securities		137,771		1,118		7,726		131,163
		7,359,445		67,944		47,049		7,380,340
Investment securities held to maturity:
U.S. Treasury and federal agencies		946,782		1,547		—		948,329
Obligations of states and political subdivisions		5,415		32		—		5,447
Mortgage-backed securities:
Government issued or guaranteed		2,543,906		37,595		4,505		2,576,996
Privately issued		104,592		11,986		20,730		95,848
Other debt securities		3,538		—		—		3,538
		3,604,233		51,160		25,235		3,630,158
Total debt securities	$	10,963,678	$	119,104	$	72,284	$	11,010,498
Equity and other securities:
Readily marketable equity — at fair value	$	114,565	$	37,558	$	322	$	151,801
Other — at cost		443,875		—		—		443,875
Total equity and other securities	$	558,440	$	37,558	$	322	$	595,676

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
	(In thousands)
December 31, 2018
Investment securities available for sale:
U.S. Treasury and federal agencies	$	1,346,782	$	—	$	9,851	$	1,336,931
Obligations of states and political subdivisions		1,660		4		5		1,659
Mortgage-backed securities:
Government issued or guaranteed		7,383,340		15,754		182,103		7,216,991
Privately issued		24		—		2		22
Other debt securities		137,617		770		11,481		126,906
		8,869,423		16,528		203,442		8,682,509
Investment securities held to maturity:
U.S. Treasury and federal agencies		446,542		—		239		446,303
Obligations of states and political subdivisions		7,494		22		12		7,504
Mortgage-backed securities:
Government issued or guaranteed		2,745,776		4,165		55,111		2,694,830
Privately issued		113,160		12,345		22,327		103,178
Other debt securities		3,668		—		—		3,668
		3,316,640		16,532		77,689		3,255,483
Total debt securities	$	12,186,063	$	33,060	$	281,131	$	11,937,992
Equity and other securities:
Readily marketable equity — at fair value	$	77,440	$	17,295	$	818	$	93,917
Other — at cost		599,747		—		—		599,747
Total equity and other securities	$	677,187	$	17,295	$	818	$	693,664

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

At June 30, 2019, 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	$	429,891		428,384
Due after one year through five years		8,048		8,048
Due after five years through ten years		102,181		99,357
Due after ten years		30,000		26,202
		570,120		561,991
Mortgage-backed securities available for sale		6,789,325		6,818,349
	$	7,359,445		7,380,340
Debt securities held to maturity:
Due in one year or less	$	948,757		950,308
Due after one year through five years		3,440		3,468
Due after ten years		3,538		3,538
		955,735		957,314
Mortgage-backed securities held to maturity		2,648,498		2,672,844
	$	3,604,233		3,630,158

Investment Securities in Continuous Unrealized Loss Position

A summary of investment securities that as of June 30, 2019 and December 31, 2018 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)
June 30, 2019
Investment securities available for sale:
U.S. Treasury and federal agencies	$	—		—			428,193		(1,538	)
Obligations of states and political subdivisions		—		—			457		(3	)
Mortgage-backed securities:
Government issued or guaranteed		4,795		(28	)		2,911,625		(37,754	)
Other debt securities		45,420		(474	)		67,921		(7,252	)
		50,215		(502	)		3,408,196		(46,547	)
Investment securities held to maturity:
Mortgage-backed securities:
Government issued or guaranteed		—		—			318,799		(4,505	)
Privately issued		—		—			50,757		(20,730	)
		—		—			369,556		(25,235	)
Total	$	50,215		(502	)		3,777,752		(71,782	)
December 31, 2018
Investment securities available for sale:
U.S. Treasury and federal agencies	$	273		(2	)		1,335,559		(9,849	)
Obligations of states and political subdivisions		629		(5	)		—		—
Mortgage-backed securities:
Government issued or guaranteed		405,558		(2,892	)		5,646,773		(179,211	)
Privately issued		22		(2	)		—		—
Other debt securities		53,478		(2,187	)		66,014		(9,294	)
		459,960		(5,088	)		7,048,346		(198,354	)
Investment securities held to maturity:
U.S. Treasury and federal agencies		446,303		(239	)		—		—
Obligations of states and political subdivisions		—		—			3,126		(12	)
Mortgage-backed securities:
Government issued or guaranteed		179,354		(989	)		2,082,723		(54,122	)
Privately issued		—		—			51,943		(22,327	)
		625,657		(1,228	)		2,137,792		(76,461	)
Total	$	1,085,617		(6,316	)		9,186,138		(274,815	)