Cash Flows (Summary of Non-Cash Activities and Other Supplemental Data) (Details) - USD ($) $ in Thousands	6 Months Ended
Jun. 30, 2021	Jun. 30, 2020
Non-Cash Investing and Financing Activities:
Finance lease additions	$ 0	$ 14,266
Capital expenditures incurred but not yet paid	1,758	1,906
Supplemental Data:
Cash interest paid	54,207	68,129
Income taxes paid, net	$ 45,058	$ 29,723

Future cash outflow to pay for purchases of fixed assets that have occurred.

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