Financial Instruments - Fair Value Assets Measured on Recurring Basis (Details) - Recurring - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Restricted investments:
Rabbi Trust	$ 51,247	$ 36,982
Marketable equity and fixed income securities	47,382	25,939
Other non-current assets	18,887	18,094
Quoted Prices in Active Markets (Level 1)
Restricted investments:
Rabbi Trust	9,547
Marketable equity and fixed income securities	19,010
Significant Other Observable Inputs (Level 2)
Restricted investments:
Rabbi Trust	41,700	36,982
Marketable equity and fixed income securities	28,372	25,939
Other non-current assets	18,887	18,094
Interest Rate Swap
Restricted investments:
Interest rate swap derivatives	3,849	4,613
Interest Rate Swap | Significant Other Observable Inputs (Level 2)
Restricted investments:
Interest rate swap derivatives	$ 3,849	$ 4,613