Other Long-Term Financial Liabilities Impact of Failed Sale Leasebacks, Income Statement (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Other Long-Term Financial Liabilities [Line Items]
Depreciation and amortization	$ 70,553	$ 68,571	$ 74,579
Interest expense	15,949	$ 19,233	$ 31,683
Failed Sale Leasebacks
Other Long-Term Financial Liabilities [Line Items]
Depreciation and amortization	766
Interest expense	$ 651