Financial Instruments - Fair Value Assets and Liabilities Measured on Recurring Basis (Details) - Recurring - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Restricted investment:
Rabbi Trusts	$ 44,712	$ 36,982
Marketable equity and fixed income securities	36,844	25,939
Quoted Prices in Active Markets (Level 1)
Restricted investment:
Rabbi Trusts	7,014
Marketable equity and fixed income securities	10,051
Significant Other Observable Inputs (Level 2)
Restricted investment:
Rabbi Trusts	37,698	36,982
Marketable equity and fixed income securities	26,793	25,939
Interest Rate Swap
Restricted investment:
Interest rate swap derivatives	3,313	4,613
Interest Rate Swap | Significant Other Observable Inputs (Level 2)
Restricted investment:
Interest rate swap derivatives	$ 3,313	$ 4,613