Fair Value Measurements (Details) - USD ($) $ in Thousands	Sep. 30, 2018	May 10, 2018	Dec. 31, 2017
Assets, Fair Value Disclosure [Abstract]
Convertible note hedge fair value	$ 0		$ 53,683
Liabilities, Fair Value Disclosure [Abstract]
Note conversion obligation fair value	0		54,359
Warrant liability	186,093		211,136
Fair Value, Measurements, Recurring [Member]
Assets, Fair Value Disclosure [Abstract]
Cash equivalents - money market	31,899		1,326
Derivative Asset	5,555		1,840
Convertible note hedge fair value			53,683
Total Assets	37,454		56,849
Liabilities, Fair Value Disclosure [Abstract]
Note conversion obligation fair value			(54,359)
Warrant liability	(186,093)		(211,136)
Total Liabilities	(186,093)		(265,495)
Carrying value, debt	542,100		515,800
Fair Value, Measurements, Recurring [Member] | Level 1 [Member]
Assets, Fair Value Disclosure [Abstract]
Cash equivalents - money market	0		0
Derivative Asset	0		0
Convertible note hedge fair value			0
Total Assets	0		0
Liabilities, Fair Value Disclosure [Abstract]
Note conversion obligation fair value			0
Warrant liability	0		0
Total Liabilities	0		0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Assets, Fair Value Disclosure [Abstract]
Cash equivalents - money market	31,899		1,326
Derivative Asset	5,555		1,840
Convertible note hedge fair value		$ 50,559	53,683
Total Assets	37,454		56,849
Liabilities, Fair Value Disclosure [Abstract]
Note conversion obligation fair value		$ (51,285)	(54,359)
Warrant liability	(186,093)		(211,136)
Total Liabilities	(186,093)		(265,495)
Difference between fair value and carrying value, debt	(7,500)		9,100
Fair Value, Measurements, Recurring [Member] | Level 3 [Member]
Assets, Fair Value Disclosure [Abstract]
Cash equivalents - money market	0		0
Derivative Asset	0		0
Convertible note hedge fair value			0
Total Assets	0		0
Liabilities, Fair Value Disclosure [Abstract]
Note conversion obligation fair value			0
Warrant liability	0		0
Total Liabilities	$ 0		$ 0