Cash Flows (Summary of Non-Cash Activities and Other Supplemental Data) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Non-Cash Investing and Financing Activities:
Finance lease additions	$ 0	$ 14,260
Capital expenditures incurred but not yet paid	1,471	2,105
Supplemental Data:
Cash interest paid	99,890	91,940
Income taxes paid, net	$ 48,941	$ 60,355