Income Taxes (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
	Jul. 31, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Operating Loss Carryforwards [Line Items]
Deferred income tax benefit		$ 467	$ 14,246	$ 1,448	$ 19,335
Deferred tax liabilities		5,732		5,732
Domestic Tax Authority
Operating Loss Carryforwards [Line Items]
Taxable loss		47,100	39,100	194,400	104,400
Current income tax expense (benefit)			(31)		82
Operating and capital loss carryforwards		564,100		564,100
Research and development tax credits		9,200		9,200
Foreign Tax Authority
Operating Loss Carryforwards [Line Items]
Current income tax expense (benefit)		(45)	(45)	(167)	$ (282)
Operating loss carryforwards		159,200		159,200
Generated After 2017
Operating Loss Carryforwards [Line Items]
Operating and capital loss carryforwards		$ 311,400		$ 311,400
3.5% Convertible Notes Due 2023
Operating Loss Carryforwards [Line Items]
Deferred income tax benefit	$ 13,367		$ 13,367