Financial Instruments - Fair Value Assets and Liabilities Measured on Recurring Basis (Details) - Recurring - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Restricted investment:
Rabbi Trusts	$ 56,681	$ 51,247
Marketable equity and fixed income securities	55,149	47,382
Other non-current assets	19,179	18,887
Quoted Prices in Active Markets (Level 1)
Restricted investment:
Rabbi Trusts	9,939	9,547
Marketable equity and fixed income securities	1,885	19,010
Significant Other Observable Inputs (Level 2)
Restricted investment:
Rabbi Trusts	46,742	41,700
Marketable equity and fixed income securities	53,264	28,372
Other non-current assets	19,179	18,887
Interest Rate Swap
Restricted investment:
Interest rate swap derivatives	3,104	3,849
Interest Rate Swap | Significant Other Observable Inputs (Level 2)
Restricted investment:
Interest rate swap derivatives	$ 3,104	$ 3,849