Supplemental Stockholders' Equity Information - Changes in Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance, beginning of period	$ 1,747,962	$ 1,576,790	$ 1,763,219	$ 1,599,972
Other comprehensive loss before reclassifications, before tax			(3,101)
Amounts reclassified from accumulated other comprehensive loss, before tax			6,603
Income tax (benefit)/expense			952
Net current-period other comprehensive (loss)/income, net of tax	2,047	2,456	2,550	6,165
Balance, end of period	1,804,986	1,607,220	1,804,986	1,607,220
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance, beginning of period			910
Other comprehensive loss before reclassifications, before tax			(2,434)
Amounts reclassified from accumulated other comprehensive loss, before tax			0
Income tax (benefit)/expense			(637)
Net current-period other comprehensive (loss)/income, net of tax			(1,797)
Balance, end of period	(887)		(887)
Funded Status of Benefit Plans
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance, beginning of period			(353,286)
Other comprehensive loss before reclassifications, before tax			0
Amounts reclassified from accumulated other comprehensive loss, before tax			6,603
Income tax (benefit)/expense			1,764
Net current-period other comprehensive (loss)/income, net of tax			4,839
Balance, end of period	(348,447)		(348,447)
Net Unrealized Loss on Available-For-Sale Securities
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance, beginning of period			(486)
Other comprehensive loss before reclassifications, before tax			(667)
Amounts reclassified from accumulated other comprehensive loss, before tax			0
Income tax (benefit)/expense			(175)
Net current-period other comprehensive (loss)/income, net of tax			(492)
Balance, end of period	(978)		(978)
Total Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance, beginning of period	(352,359)	(354,138)	(352,862)	(357,847)
Net current-period other comprehensive (loss)/income, net of tax	2,047	2,456	2,550	6,165
Balance, end of period	$ (350,312)	$ (351,682)	$ (350,312)	$ (351,682)