Additional Balance Sheet Detail and Supplemental Cash Flow Information (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Supplemental Cash Flow Information [Abstract]
Finance Lease Obligations	$ 5,283	$ 16,615	$ 45,813
Capital Expenditures Incurred but Not yet Paid	30,682	8,188	6,428
Extinguishment of Debt	0	20,009	0
Non-cash acquisitions and related deferred taxes	0	0	110,273
Non-cash Permit contingent consideration	5,295	5,973	0
Interest Paid	20,634	24,428	22,916
Income Taxes Paid	$ 35,600	$ 33,700	$ 50,400