Accumulated Other Comprehensive Income (Loss) - Schedule of accumulated other comprehensive income (loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Accumulated Other Comprehensive Income (Loss)
Beginning Balance	$ 1,425,564	$ 1,188,708	$ 1,365,580	$ 683,866
Tax effect	16,781	474	66,839	1,424
Ending Balance	1,396,150	1,186,061	1,396,150	1,186,061
Accumulated Other Comprehensive Income (loss)
Accumulated Other Comprehensive Income (Loss)
Beginning Balance	56,880	6,680	61,429	14,158
Unrealized (losses)			(46)
Amounts reclassified from accumulated other comprehensive income (loss)			(15,499)
Tax effect			3,415
Ending Balance	49,299	$ 5,203	49,299	$ 5,203
Pension, Postretirement and Other Post-Employment Benefits
Accumulated Other Comprehensive Income (Loss)
Beginning Balance			61,485
Amounts reclassified from accumulated other comprehensive income (loss)			(15,560)
Tax effect			3,419
Ending Balance	49,344		49,344
Available-for-Sale Securities
Accumulated Other Comprehensive Income (Loss)
Beginning Balance			(56)
Unrealized (losses)			(46)
Amounts reclassified from accumulated other comprehensive income (loss)			61
Tax effect			(4)
Ending Balance	$ (45)		$ (45)