Long-Term Obligations and Commitments, Long-Term Obligations (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Long-Term Obligations [Abstract]
Total long-term obligations, including current portion	$ 589,105	$ 464,443
Less: current portion	(1,185)	(515)
Total Long-Term Obligations	587,920	463,928
1 Percent Convertible Senior Notes [Member]
Long-Term Obligations [Abstract]
Total long-term obligations, including current portion	500,511	339,847
2 3/4 Percent Convertible Senior Notes [Member]
Long-Term Obligations [Abstract]
Total long-term obligations, including current portion	124	49,523
Long-term Financing Liability for Leased Facility [Member]
Long-Term Obligations [Abstract]
Total long-term obligations, including current portion	72,359	72,217
Fixed Rate Note with Morgan Stanley [Member]
Long-Term Obligations [Abstract]
Total long-term obligations, including current portion	12,500	0
Leases and Other Obligations [Member]
Long-Term Obligations [Abstract]
Total long-term obligations, including current portion	$ 3,611	$ 2,856