Pension Plans and Other Postretirement Benefits - Fair Values of Company's Pension Plan Assets by Asset Category (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	$ 2,938,404	$ 2,593,533
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	2,041,465	1,807,358
Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	488,528	437,136
Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	408,411	349,039
Money-Market Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	89,829	82,751
Money-Market Investments [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	52,005	43,616
Money-Market Investments [Member] | Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	37,824	39,135
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	1,342,754	1,260,216
Equity Securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	1,342,754	1,260,216
M&T Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	118,285	134,447
M&T Equity Securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	118,285	134,447
Domestic Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	449,466	369,283
Domestic Equity Securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	449,466	369,283
International Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	18,510	14,835
International Equity Securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	18,510	14,835
Domestic Mutual Fund Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	279,299	280,347
Domestic Mutual Fund Equity Securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	279,299	280,347
International Mutual Fund Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	477,194	461,304
International Mutual Fund Equity Securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	477,194	461,304
Total Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	873,319	713,425
Total Debt Securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	422,615	315,424
Total Debt Securities [Member] | Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	450,704	398,001
Corporate Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	199,728	178,528
Corporate Debt Securities [Member] | Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	199,728	178,528
Government Agency [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	236,199	206,540
Government Agency [Member] | Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	236,199	206,540
Non-U.S. Government [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	14,777	12,933
Non-U.S. Government [Member] | Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	14,777	12,933
Domestic Mutual Fund Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	422,615	315,424
Domestic Mutual Fund Debt Securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	422,615	315,424
Other Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	632,502	537,141
Other Securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	224,091	188,102
Other Securities [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	408,411	349,039
Other Diversified Mutual Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	108,483	108,239
Other Diversified Mutual Fund [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	108,483	108,239
Other Real Estate Partnerships [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	26,953	16,620
Other Real Estate Partnerships [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	6,651	5,264
Other Real Estate Partnerships [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	20,302	11,356
Other Private Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	211,098	151,550
Other Private Equity [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	211,098	151,550
Other Hedge Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	276,367	250,691
Other Hedge Funds [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	108,957	74,599
Other Hedge Funds [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	167,410	176,092
Guaranteed Deposit Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	9,601	10,041
Guaranteed Deposit Fund [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	$ 9,601	$ 10,041