Financial Commitments (Summary of Interest Expense as Reported in the Consolidated Statements of Operations) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Debt Instrument [Line Items]
Other interest	$ 409	$ 535	$ 890	$ 1,039
Total cash interest expense	16,087	12,904	31,880	25,854
Non-cash interest expense			3,868	7,046
Total non-cash interest expense	1,851	3,560	3,868	7,046
Total interest expense	17,938	16,464	35,748	32,900
Term Loan B
Debt Instrument [Line Items]
Cash interest expense	6,115		12,209
Non-cash interest expense	$ 527		$ 1,066
Effective interest rates	6.49%		6.49%
Convertible Notes
Debt Instrument [Line Items]
Cash interest expense	$ 418	1,438	$ 921	2,875
Non-cash interest expense	$ 941	2,933	$ 2,040	5,797
Effective interest rates	9.39%		9.39%
2017 Senior Notes | Senior Notes
Debt Instrument [Line Items]
Cash interest expense	$ 8,593	8,593	$ 17,187	17,187
Non-cash interest expense	$ 241	225	$ 478	445
Effective interest rates	7.13%		7.13%
2020 Revolver
Debt Instrument [Line Items]
Cash interest expense	$ 552		$ 673
Non-cash interest expense	$ 142		$ 284
2017 Credit Facility | Revolving Credit Facility
Debt Instrument [Line Items]
Cash interest expense		2,338		4,753
Non-cash interest expense		$ 402		$ 804