Fair Value Measurements (Estimated Fair Values of Financial Instruments) (Details) - USD ($) $ in Thousands		Mar. 31, 2024	Dec. 31, 2023
Carrying Amount [Member] | Level 2 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long-term debt, including current portion	[1]	$ (1,035,817)	$ (1,035,654)
Carrying Amount [Member] | Level 2 [Member] | Interest rate contracts [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative assets related to interest rate swaps		142,636	129,125
Carrying Amount [Member] | Level 2 [Member] | Term Loans [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long-term debt, including current portion		(970,082)	(969,919)
Carrying Amount [Member] | Level 2 [Member] | Revenue bonds [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long-term debt, including current portion		(65,735)	(65,735)
Carrying Amount [Member] | Level 3 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Company owned life insurance asset (COLI)		5,361	5,220
Fair Value [Member] | Level 2 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long-term debt, including current portion	[1]	(1,030,852)	(1,030,504)
Fair Value [Member] | Level 2 [Member] | Interest rate contracts [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative assets related to interest rate swaps		142,636	129,125
Fair Value [Member] | Level 2 [Member] | Term Loans [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long-term debt, including current portion		(966,066)	(965,718)
Fair Value [Member] | Level 2 [Member] | Revenue bonds [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long-term debt, including current portion		(64,786)	(64,786)
Fair Value [Member] | Level 3 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Company owned life insurance asset (COLI)		$ 5,361	$ 5,220

[1] The carrying amount of long-term debt includes principal and unamortized discounts.