Derivative Contracts - Losses and Gains on Derivative Instruments (Details) - Not Designated as Hedging Instrument - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivative instruments	$ 174	$ 3,043	$ 52
Common stock options/warrants
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivative instruments	(601)	2,643	(2,533)
2033 Senior Notes
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivative instruments	0	0	3,185
Forward contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivative instruments	$ 775	$ 400	$ (600)