Stockholder's Equity - Accumulated Other Comprehensive Income (Loss) - Reclassifications of Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Amortization of pension and postretirement items:
Tax benefit	$ (9,000)	$ (6,800)	$ (27,400)	$ (23,400)
Derivative, Gain (Loss) on Derivative, Net	200	100	1,000	1,400
Proceeds from Issuance of Common Stock, Dividend Reinvestment Plan			61,200	2,500
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	$ 100	$ 100	$ 200	$ 300