Stockholder's Equity - Accumulated Other Comprehensive Income (Loss) - Reclassifications of Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Amortization of pension and postretirement items:
Tax benefit	$ (6,789)	$ (3,673)	$ (30,191)	$ (21,368)
Derivative, Gain (Loss) on Derivative, Net	150	(292)	1,535	74
Proceeds from Issuance of Common Stock, Dividend Reinvestment Plan			56,800
Interest Rate Swap [Member] | Derivatives designated as hedging instrument [Member] | Interest Expense [Member]
Amortization of pension and postretirement items:
Derivative, Gain (Loss) on Derivative, Net	$ 237	$ 160	$ 579	$ 352