Pension plans and other postretirement benefits (Tables)

12 Months Ended

Dec. 31, 2016

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
	2016			2015			2014
	(In thousands)
Service cost	$	25,037		$	24,372		$	20,520
Interest cost on benefit obligation		83,410			72,731			69,162
Expected return on plan assets		(108,473	)		(96,155	)		(91,568	)
Amortization of prior service credit		(3,228	)		(6,005	)		(6,552	)
Recognized net actuarial loss		30,145			44,825			14,494
Net periodic pension expense	$	26,891		$	39,768		$	6,056

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

	Year Ended December 31
	2016			2015			2014
	(In thousands)
Service cost	$	1,595		$	914		$	605
Interest cost on benefit obligation		4,971			2,995			2,778
Amortization of prior service credit		(1,359	)		(1,359	)		(1,359	)
Recognized net actuarial loss		60			106			—
Net other postretirement benefits expense	$	5,267		$	2,656		$	2,024

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
	2016			2015			2016			2015
	(In thousands)
Change in benefit obligation:
Benefit obligation at beginning of year	$	2,004,531		$	1,813,409		$	121,497		$	67,502
Service cost		25,037			24,372			1,595			914
Interest cost		83,410			72,731			4,971			2,995
Plan participants’ contributions		—			—			3,085			2,619
Amendments and curtailments		(28,308	)		—			—			—
Actuarial (gain) loss		4,827			(83,593	)		(10,553	)		(2,431	)
Business combinations		—			247,340			—			56,539
Medicare Part D reimbursement		—			—			592			420
Benefits paid		(82,339	)		(69,728	)		(11,265	)		(7,061	)
Benefit obligation at end of year		2,007,158			2,004,531			109,922			121,497
Change in plan assets:
Fair value of plan assets at beginning of year		1,625,134			1,505,661			—			—
Actual return on plan assets		88,564			(14,069	)		—			—
Employer contributions		10,772			8,367			7,588			4,022
Plan participants’ contributions		—			—			3,085			2,619
Business combinations		—			194,903			—			—
Medicare Part D reimbursement		—			—			592			420
Benefits paid		(82,339	)		(69,728	)		(11,265	)		(7,061	)
Fair value of plan assets at end of year		1,642,131			1,625,134			—			—
Funded status	$	(365,027	)	$	(379,397	)	$	(109,922	)	$	(121,497	)
Accrued liabilities recognized in the consolidated    balance sheet	$	(365,027	)	$	(379,397	)	$	(109,922	)	$	(121,497	)
Amounts recognized in accumulated other    comprehensive income (“AOCI”) were:
Net loss (gain)	$	460,562		$	494,279		$	(6,413	)	$	4,200
Net prior service cost (credit)		3,505			277			(7,737	)		(9,096	)
Pre-tax adjustment to AOCI		464,067			494,556			(14,150	)		(4,896	)
Taxes		(182,611	)		(194,608	)		5,568			1,927
Net adjustment to AOCI	$	281,456		$	299,948		$	(8,582	)	$	(2,969	)

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)
2016
Net loss (gain)	$	24,736		$	(10,553	)	$	14,183
Amendments and curtailments		(28,308	)		—			(28,308	)
Amortization of prior service credit		3,228			1,359			4,587
Amortization of actuarial loss		(30,145	)		(60	)		(30,205	)
Total recognized in other comprehensive income,    pre-tax	$	(30,489	)	$	(9,254	)	$	(39,743	)
2015
Net loss (gain)	$	26,631		$	(2,431	)	$	24,200
Amortization of prior service credit		6,005			1,359			7,364
Amortization of actuarial loss		(44,825	)		(106	)		(44,931	)
Total recognized in other comprehensive income,    pre-tax	$	(12,189	)	$	(1,178	)	$	(13,367	)

Amortization of Amounts in Accumulated Other Comprehensive Income Expected to be Recognized as Components of Net Periodic Benefit Expense

The following table reflects the amortization of amounts in accumulated other comprehensive income expected to be recognized as components of net periodic benefit expense during 2017:

	Pension Plans		Other Postretirement Benefit Plans
	(In thousands)
Amortization of net prior service cost (credit)	$	557	$	(1,359	)
Amortization of net loss (gain)		27,196		(44	)

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
	2016			2015			2016			2015
Discount rate		4.00	%		4.25	%		4.00	%		4.25	%
Rate of increase in future compensation levels		4.39	%		4.37	%		—			—

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
	2016			2015			2014			2016			2015			2014
Discount rate		4.25	%		4.00	%		4.75	%		4.25	%		4.00	%		4.75	%
Long-term rate of return on plan assets		6.50	%		6.50	%		6.50	%		—			—			—
Rate of increase in future compensation    levels		4.37	%		4.39	%		4.42	%		—			—			—

Effects on One-Percentage Point Change in Assumed Health Care Cost Trend Rates

A one-percentage point change in assumed health care cost trend rates would have had the following effects:

	+1%			-1%
	(In thousands)
Increase (decrease) in:
Service and interest cost	$	106	$	(87	)
Accumulated postretirement benefit obligation		1,548		(1,400	)

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

The fair values of the Company’s pension plan assets at December 31, 2016, by asset category, were as follows:

	Fair Value Measurement of Plan Assets At December 31, 2016
	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 funds	$	39,556	$	35,562	$	3,994	$	—
Equity securities:
M&T		164,474		164,474		—		—
Domestic(a)		200,595		200,595		—		—
International(b)		14,364		14,364		—		—
Mutual funds:
Domestic(a)		250,472		250,472		—		—
International(b)		290,172		290,172		—		—
		920,077		920,077		—		—
Debt securities:
Corporate(c)		104,909		—		104,909		—
Government		121,869		—		121,869		—
International		13,073		—		13,073		—
Mutual funds:
Domestic(d)		205,847		205,847		—		—
		445,698		205,847		239,851		—
Other:
Diversified mutual fund		92,691		92,691		—		—
Real estate partnerships		3,112		768		—		2,344
Private equity		21,924		—		—		21,924
Hedge funds		106,250		85,270		—		20,980
Guaranteed deposit fund		10,992		—		—		10,992
		234,969		178,729		—		56,240
Total(e)	$	1,640,300	$	1,340,215	$	243,845	$	56,240

The fair values of the Company’s pension plan assets at December 31, 2015, by asset category, were as follows:

	Fair Value Measurement of Plan Assets At December 31, 2015
	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 funds	$	69,634	$	37,958	$	31,676	$	—
Equity securities:
M&T		148,800		148,800		—		—
Domestic(a)		106,993		106,993		—		—
International(b)		9,433		9,433		—		—
Mutual funds:
Domestic(a)		445,663		445,663		—		—
International(b)		348,869		348,869		—		—
		1,059,758		1,059,758		—		—
Debt securities:
Corporate(c)		105,499		—		105,499		—
Government		120,346		—		120,346		—
International		7,492		—		7,492		—
Mutual funds:
Domestic(d)		51,028		51,028		—		—
		284,365		51,028		233,337		—
Other:
Diversified mutual fund		70,343		70,343		—		—
Real estate partnerships		2,787		—		—		2,787
Private equity		5,603		—		—		5,603
Hedge funds		119,549		81,861		—		37,688
Guaranteed deposit fund		11,596		—		—		11,596
		209,878		152,204		—		57,674
Total(e)	$	1,623,635	$	1,300,948	$	265,013	$	57,674

(a) This category is comprised of equities of companies primarily within the 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 markets in Europe and the Pacific Rim.

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

(d) Approximately 75% of the mutual funds were invested in investment grade bonds and 25% in high-yielding bonds at December 31, 2016. Approximately 33% of the mutual funds were invested in investment grade bonds and 67% in high-yielding bonds at December 31, 2015. The holdings within the funds were spread across diverse industries.

(e) Excludes dividends and interest receivable totaling $1,831,000 and $1,499,000 at December 31, 2016 and 2015, respectively.

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, 2016 were as follows:

	Balance – January 1, 2016		Purchases (Sales)			Total Realized/ Unrealized Gains (Losses)			Balance – December 31, 2016
	(In thousands)
Other
Private real estate	$	2,787	$	(1,111	)	$	668		$	2,344
Private equity		5,603		17,177			(856	)		21,924
Hedge funds		37,688		(16,337	)		(371	)		20,980
Guaranteed deposit fund		11,596		(540	)		(64	)		10,992
Total	$	57,674	$	(811	)	$	(623	)	$	56,240

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:
2017	$	81,927	$	8,142
2018		85,715		8,220
2019		91,819		8,251
2020		96,465		8,259
2021		101,698		8,235
2022 through 2026		568,830		40,282