Fair Value Measurements (Schedule of Fair Values of Financial Instruments and Nonfinancial Assets and Liabilities Measured at the Reporting Date) (Details) - Fuel Hedge Contracts [Member] - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair Value, Net Asset (Liability)	$ 8,971	$ 630
Significant Other Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair Value, Net Asset (Liability)	$ 8,971	$ 630