Long-Term Debt Schedule of Long-Term Debt Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Feb. 16, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Total	$ 115,840		$ 267
Other debt	594		191
Less: current maturities	(106)		(111)
Long-term debt, less current portion	$ 115,734		$ 156
4.50% Exchangeable Senior Notes Due 2023
Debt Instrument [Line Items]
Interest rate	4.50%	4.50%	4.50%
Senior Notes
Debt Instrument [Line Items]
Less: unamortized debt discount and issuance costs, net	$ (28,059)		$ 0
Total	115,691		0
Equity component of exchangeable notes, net of issuance costs	(26,699)		0
Senior Notes | 4.50% Exchangeable Senior Notes Due 2023
Debt Instrument [Line Items]
Long-term debt	143,750		0
Loans Payable
Debt Instrument [Line Items]
Other debt	$ 149		$ 267