Income Taxes - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Operating Loss Carryforwards [Line Items]
Deferred tax liabilities	$ 2,698		$ 2,698
Domestic
Operating Loss Carryforwards [Line Items]
Taxable loss	(27,700)	$ (55,700)	(107,000)	$ (147,300)
Operating loss carryforwards	675,200		675,200
Deferred tax assets, capital loss carryforwards	199,700		199,700
Research and development tax credits	10,100		10,100
Foreign
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	74,200		74,200
Generated After 2017
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	$ 422,500		$ 422,500