Lease Accounting (Lease Balances by Major Categories) (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Operating Leased Assets [Line Items]
Total Right of Use Assets, net	$ 140,796	$ 153,925
Accrued liabilities, current	19,966	23,348
Other long-term liabilities, non-current	121,854	131,623
Present value of operating lease liabilities	$ 141,820	$ 154,971
Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Accrued liabilities	Accrued liabilities
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]	OTHER LONG-TERM LIABILITIES	OTHER LONG-TERM LIABILITIES
Transportation equipment
Operating Leased Assets [Line Items]
Total Right of Use Assets, net	$ 79,784	$ 88,038
Present value of operating lease liabilities	79,716
Office Space and Equipment
Operating Leased Assets [Line Items]
Total Right of Use Assets, net	5,981	7,489
Present value of operating lease liabilities	6,155
Facilities and Equipment
Operating Leased Assets [Line Items]
Total Right of Use Assets, net	55,031	$ 58,398
Present value of operating lease liabilities	$ 55,949