Retirement Plans and Other Postretirement Benefits - Schedule of Net Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Amortization of:
Portion of cost/(benefit) charged to expense	$ (12,188)	$ (10,174)	$ (36,633)	$ (30,513)
Pension Benefits
Retirement Plans and Other Benefits
Service cost — benefits earned during the period	10,910	9,865	32,731	29,595
Interest cost on benefit obligation	37,161	38,390	111,482	115,170
Expected return on plan assets	(47,163)	(45,735)	(141,488)	(137,204)
Amortization of:
Prior service credit	0	0	0	0
Net actuarial loss/(gain)	10,479	9,605	31,437	28,815
Net periodic cost/(benefit)	11,387	12,125	34,162	36,376
Portion of cost/(benefit) charged to expense	5,828	6,828	17,665	20,568
Other Benefits
Retirement Plans and Other Benefits
Service cost — benefits earned during the period	2,489	2,142	7,466	6,426
Interest cost on benefit obligation	5,542	5,627	16,627	16,882
Expected return on plan assets	(11,709)	(10,872)	(35,126)	(32,616)
Amortization of:
Prior service credit	(9,447)	(9,447)	(28,341)	(28,341)
Net actuarial loss/(gain)	(2,169)	(2,404)	(6,507)	(7,211)
Net periodic cost/(benefit)	(15,294)	(14,954)	(45,881)	(44,860)
Portion of cost/(benefit) charged to expense	$ (11,396)	$ (10,851)	$ (34,217)	$ (32,536)