Pension plans and other postretirement benefits (Tables)

12 Months Ended

Dec. 31, 2020

Compensation And Retirement Disclosure [Abstract]

Net Periodic Pension Expense for Defined Benefit Plans

Net periodic pension expense for defined benefit plans consisted of the following:

	Year Ended December 31
	2020			2019			2018
	(In thousands)
Service cost	$	19,944		$	17,294		$	20,346
Interest cost on benefit obligation		71,421			81,579			74,704
Expected return on plan assets		(125,512	)		(122,139	)		(123,127	)
Amortization of prior service cost		557			557			557
Recognized net actuarial loss		58,096			21,992			43,793
Net periodic pension cost (benefit)	$	24,506		$	(717	)	$	16,273

Net other postretirement benefits expense for defined benefit plans consisted of the following:

	Year Ended December 31
	2020			2019			2018
	(In thousands)
Service cost	$	970		$	859		$	938
Interest cost on benefit obligation		1,741			2,344			2,293
Amortization of prior service credit		(4,738	)		(4,730	)		(4,729	)
Recognized net actuarial gain		(1,236	)		(1,247	)		(826	)
Net other postretirement benefits	$	(3,263	)	$	(2,774	)	$	(2,324	)

Data Relating to Funding Position of Defined Benefit Plans

Data relating to the funding position of the defined benefit plans were as follows:

	Pension Benefits						Other Postretirement Benefits
	2020			2019			2020			2019
	(In thousands)
Change in benefit obligation:
Benefit obligation at beginning of year	$	2,247,329		$	1,949,613		$	56,492		$	59,991
Service cost		19,944			17,294			970			859
Interest cost		71,421			81,579			1,741			2,344
Plan participants’ contributions		—			—			2,386			2,749
Actuarial (gain) loss		288,944			298,713			2,371			(687	)
Medicare Part D reimbursement		—			—			574			370
Benefits paid		(106,346	)		(99,870	)		(9,253	)		(9,134	)
Benefit obligation at end of year		2,521,292			2,247,329			55,281			56,492
Change in plan assets:
Fair value of plan assets at beginning of    year		2,037,940			1,833,833			—			—
Actual return on plan assets		178,610			293,546			—			—
Employer contributions		310,378			10,431			6,293			6,015
Plan participants’ contributions		—			—			2,386			2,749
Medicare Part D reimbursement		—			—			574			370
Benefits paid		(106,346	)		(99,870	)		(9,253	)		(9,134	)
Fair value of plan assets at end of year		2,420,582			2,037,940			—			—
Funded status	$	(100,710	)	$	(209,389	)	$	(55,281	)	$	(56,492	)
Prepaid asset recognized in the    consolidated balance sheet		64,670			—			—			—
Accrued liability recognized in the    consolidated balance sheet		(165,380	)		(209,389	)		(55,281	)		(56,492	)
Net accrued liability recognized in    the consolidated balance sheet	$	(100,710	)	$	(209,389	)	$	(55,281	)	$	(56,492	)
Amounts recognized in accumulated other    comprehensive income (“AOCI”) were:
Net loss (gain)	$	684,780		$	507,029		$	(13,701	)	$	(17,308	)
Net prior service cost (credit)		1,277			1,834			(22,269	)		(27,007	)
Pre-tax adjustment to AOCI		686,057			508,863			(35,970	)		(44,315	)
Taxes		(178,375	)		(133,779	)		9,352			11,650
Net adjustment to AOCI	$	507,682		$	375,084		$	(26,618	)	$	(32,665	)

Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income

The table below reflects the changes in plan assets and benefit obligations recognized in other comprehensive income related to the Company’s postretirement benefit plans.

	Pension Plans			Other Postretirement Benefit Plans			Total
	(In thousands)
2020
Net loss	$	235,847		$	2,371		$	238,218
Amortization of prior service (cost) credit		(557	)		4,738			4,181
Amortization of actuarial (loss) gain		(58,096	)		1,236			(56,860	)
Total recognized in other comprehensive income,    pre-tax	$	177,194		$	8,345		$	185,539
2019
Net loss (gain)	$	127,305		$	(687	)	$	126,618
Amortization of prior service (cost) credit		(557	)		4,730			4,173
Amortization of actuarial (loss) gain		(21,992	)		1,247			(20,745	)
Total recognized in other comprehensive income,    pre-tax	$	104,756		$	5,290		$	110,046

Assumed Weighted-Average Rates Used to Determine Benefit Obligations

The assumed weighted-average rates used to determine benefit obligations at December 31 were:

	Pension Benefits						Other Postretirement Benefits
	2020			2019			2020			2019
Discount rate		2.50	%		3.25	%		2.50	%		3.25	%
Rate of increase in future compensation levels		3.37	%		4.29	%		—			—

Assumed Weighted-Average Rates Used to Determine Net Benefit Expense

The assumed weighted-average rates used to determine net benefit expense for the years ended December 31 were:

	Pension Benefits									Other Postretirement Benefits
	2020			2019			2018			2020			2019			2018
Discount rate		3.25	%		4.25	%		3.50	%		3.25	%		4.25	%		3.50	%
Long-term rate of return on plan assets		6.50	%		6.50	%		6.50	%		—			—			—
Rate of increase in future compensation    levels		4.29	%		4.31	%		4.33	%		—			—			—

Fair Values of Company's Pension Plan Assets by Asset Category

The fair values of the Company’s pension plan assets at December 31, 2020 and 2019, by asset category, were as follows:

	Fair Value Measurement of Plan Assets At December 31, 2020
	Total		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
	(In thousands)
Asset category:
Money-market investments	$	65,263	$	48,322	$	16,941	$	—
Equity securities:
M&T		111,441		111,441		—		—
Domestic(a)		308,220		308,220		—		—
International(b)		13,648		13,648		—		—
Mutual funds:
Domestic(a)		302,094		302,094		—		—
International(b)		422,601		422,601		—		—
		1,158,004		1,158,004		—		—
Debt securities:
Corporate(c)		172,762		—		172,762		—
Government		234,232		—		234,232		—
International		6,413		—		6,413		—
Mutual funds:
Domestic(d)		302,635		302,635		—		—
		716,042		302,635		413,407		—
Other:
Diversified mutual fund		83,507		83,507		—		—
Real estate partnerships		26,847		3,616		—		23,231
Private equity / debt		97,124		—		—		97,124
Hedge funds		261,417		108,516		—		152,901
Guaranteed deposit fund		10,498		—		—		10,498
		479,393		195,639		—		283,754
Total(e)	$	2,418,702	$	1,704,600	$	430,348	$	283,754

	Fair Value Measurement of Plan Assets At December 31, 2019
	Total		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
	(In thousands)
Asset category:
Money-market investments	$	38,461	$	33,870	$	4,591	$	—
Equity securities:
M&T		148,603		148,603		—		—
Domestic(a)		219,663		219,663		—		—
International(b)		10,476		10,476		—		—
Mutual funds:
Domestic(a)		238,872		238,872		—		—
International(b)		381,433		381,433		—		—
		999,047		999,047		—		—
Debt securities:
Corporate(c)		112,783		—		112,783		—
Government		190,679		—		190,679		—
International		6,648		—		6,648		—
Mutual funds:
Domestic(d)		249,075		249,075		—		—
		559,185		249,075		310,110		—
Other:
Diversified mutual fund		86,980		86,980		—		—
Real estate partnerships		21,905		3,939		—		17,966
Private equity / debt		87,966		—		—		87,966
Hedge funds		231,807		116,029		—		115,778
Guaranteed deposit fund		10,527		—		—		10,527
		439,185		206,948		—		232,237
Total(e)	$	2,035,878	$	1,488,940	$	314,701	$	232,237

(a) This category is mainly comprised of equities of companies primarily within the small-cap, mid-cap and large-cap sectors of the U.S. economy and range across diverse industries.

(b) This category is comprised of equities in companies primarily within the mid-cap and large-cap sectors of international markets mainly in developed and emerging markets in Europe and the Pacific Rim.

(c) This category represents investment grade bonds of U.S. issuers from diverse industries.

(d) Approximately 78% of the mutual funds were invested in investment grade bonds and 22% in high-yielding bonds at December 31, 2020. Approximately 80% of the mutual funds were invested in investment grade bonds and 20% in high-yielding bonds at December 31, 2019.  The holdings within the funds were spread across diverse industries.

(e) Excludes dividends and interest receivable totaling $2 million at each of December 31, 2020 and 2019.

Changes in Level 3 Pension Plan Assets Measured at Fair Value on Recurring Basis

The changes in Level 3 pension plan assets measured at estimated fair value on a recurring basis during the year ended December 31, 2020 were as follows:

	Balance – January 1, 2020		Purchases (Sales)		Total Realized/ Unrealized Gains (Losses)			Balance – December 31, 2020
	(In thousands)
Other
Real estate partnerships	$	17,966	$	3,581	$	1,684		$	23,231
Private equity/debt		87,966		7,206		1,952			97,124
Hedge funds		115,778		30,000		7,123			152,901
Guaranteed deposit fund		10,527		—		(29	)		10,498
Total	$	232,237	$	40,787	$	10,730		$	283,754

Defined Benefit Plan Estimated Future Benefit Payments

Estimated benefits expected to be paid in future years related to the Company’s defined benefit pension and other postretirement benefits plans are as follows:

	Pension Benefits		Other Postretirement Benefits
	(In thousands)
Year ending December 31:
2021	$	106,285	$	3,238
2022		109,880		3,269
2023		114,938		3,131
2024		119,402		2,974
2025		121,456		2,789
2026 through 2030		645,515		10,656