Additional Balance Sheet Detail and Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands		Mar. 31, 2021	Dec. 31, 2020
Other Liabilities Disclosure [Abstract]
Other Accrued Liabilities		$ 3,608	$ 3,327
Unrealized Gain (Loss) on Derivatives		148	24,950
Accrued Income Taxes, Current		12,099	26,118
Accrual for Taxes Other than Income Taxes, Current		3,315	3,616
Interest Payable, Current		2,131	1,855
Accrued Salaries, Current		21,028	30,457
Deferred Revenue	[1]	8,555	16,425
Accrued liabilities and other		$ 62,682	$ 119,158

[1] See Note 17 -- Commitments and Contingencies for additional details on deferred revenue liabilities