Going Concern (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Net loss	$ (43,218)	$ (46,352)
Net Cash Used In Operating Activities	(50,607)	$ (66,075)
Cash Cash EquivalentsMarketable Securities Restricted Cash and Restricted Cash Equivalents	$ 108,700
Accounting Year 2018 [Member]
Net loss			$ 184,700
Net Cash Used In Operating Activities			$ 184,800