Long-Term Obligations and Commitments, Long-Term Obligations (Details) - USD ($) $ in Thousands	Dec. 31, 2018		Dec. 31, 2017
Long-Term Obligations [Abstract]
Total long-term obligations, including current portion	$ 646,720		$ 607,477
Less: current portion	(13,749)		(1,621)
Total Long-Term Obligations	632,971		605,856
1 Percent Convertible Senior Notes [Member]
Long-Term Obligations [Abstract]
Total long-term obligations, including current portion	568,215		533,111
Long-term Mortgage Debt [Member]
Long-Term Obligations [Abstract]
Total long-term obligations, including current portion	59,842		59,771
Fixed Rate Note with Morgan Stanley [Member]
Long-Term Obligations [Abstract]
Total long-term obligations, including current portion	12,500	[1]	12,500
Less: current portion	(12,500)
Leases and Other Obligations [Member]
Long-Term Obligations [Abstract]
Total long-term obligations, including current portion	$ 6,163		$ 2,095

[1] Our $12.5 million fixed rate note with Morgan Stanley is included in our current portion of long-term obligations on our consolidated balance sheet at December 31, 2018.