Financial Instruments - Fair Value Assets and Liabilities Measured on Recurring Basis (Details) - Recurring - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Restricted investments:
Rabbi Trust	$ 40,752	$ 42,937
Marketable equity and fixed income securities	17,845	11,551
Fixed income securities		1,927
Significant Other Observable Inputs (Level 2)
Restricted investments:
Rabbi Trust	40,752	42,937
Marketable equity and fixed income securities	17,845	11,551
Fixed income securities		1,927
Interest Rate Swap
Liabilities:
Interest rate swap derivatives	76	3,195
Interest Rate Swap | Significant Other Observable Inputs (Level 2)
Liabilities:
Interest rate swap derivatives	$ 76	$ 3,195