Fair Value Measurements (Financial Assets and Liabilities Measured on a Recurring Basis at Fair Value) (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets, fair value, recurring		$ 2,321
Liabilities, fair value, recurring	$ 7,704
Fair Value, Inputs, Level 1 [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets, fair value, recurring		2,296
Fair Value, Inputs, Level 3 [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets, fair value, recurring		25
Liabilities, fair value, recurring	7,704
Interest Rate Swap [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Liabilities, fair value, recurring	6,418	3,825
Interest Rate Swap [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Liabilities, fair value, recurring	6,418	3,825
Marketable Securities - Restricted [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets, fair value, recurring		2,296
Marketable Securities - Restricted [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets, fair value, recurring		2,296
Fuel [Member] | Fuel Hedge [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets, fair value, recurring		25
Liabilities, fair value, recurring	1,286
Fuel [Member] | Fuel Hedge [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets, fair value, recurring		$ 25
Liabilities, fair value, recurring	$ 1,286