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, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Amortization of pension and postretirement items:
Tax benefit	$ (6,816)	$ (6,080)	$ (23,402)	$ (17,695)
Derivative, Gain (Loss) on Derivative, Net	129	(305)	1,385	366
Proceeds from Issuance of Common Stock, Dividend Reinvestment Plan			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	$ 170	$ 127	$ 342	$ 192