v3.10.0.1
Income Taxes - Additional Information (Details) - USD ($)
 12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Income Taxes [Line Items]      
Income tax benefit (expense) $ (2,547,000) $ 18,342,000 $ 7,080,000
Corporate income tax rate 21.00% 34.00% 34.00%
Pre-Tax Act U.S. federal net operating loss carry-forwards beginning of expiration year 2031    
Pre-Tax Act U.S. state net operating loss carry-forwards beginning of expiration year 2026    
U.S. Federal research tax credits beginning of expiration year 2032    
Deferred tax assets, valuation allowance $ 1,502,346,000 $ 1,144,543,000  
Gross unrecognized tax benefits, including related interest and penalties 252,068,000 203,257,000  
Net unrecognized tax benefits 251,808,000 203,177,000 $ 243,862,000
Amount of tax benefit when gross unrecognized tax benefits realized 4,100,000    
Reasonably possible unrecognized tax benefits within the next 12 months 0    
Other Liabilities      
Income Taxes [Line Items]      
Net unrecognized tax benefits $ 2,700,000 $ 2,100,000  
Federal      
Income Taxes [Line Items]      
Corporate income tax rate 21.00% 34.00%  
Reduction in net deferred tax assets $ 393,400,000 $ 396,200,000  
Change in valuation allowance 393,400,000 396,200,000  
Net operating loss carry-forwards 2,800,000,000    
Pre-Tax Act operating loss carry-forwards   $ 1,500,000,000  
Post-Tax Act operating loss carry-forwards $ 1,300,000,000    
Pre-Tax Act operating loss carry-forwards period   20 years  
Percentage of taxable income limitation 80.00%    
Federal | Research      
Income Taxes [Line Items]      
Accumulated research tax credits $ 159,800,000    
State      
Income Taxes [Line Items]      
Net operating loss carry-forwards 1,500,000,000    
State | Research      
Income Taxes [Line Items]      
Accumulated research tax credits 90,500,000    
U.K.      
Income Taxes [Line Items]      
Net operating loss carry-forwards $ 911,600,000