Annual report pursuant to Section 13 and 15(d)

Provision for Income Taxes - Narrative (Details)

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Provision for Income Taxes - Narrative (Details) - USD ($)
 12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Income Tax Disclosure [Abstract]      
Decrease in income tax provision $ 1,300,000    
Release of valuation allowance as a result of acquisitions 1,900,000 $ 1,800,000  
Operating Loss Carryforwards [Line Items]      
Increase in valuation allowance $ (108,000,000.0)    
Document Period End Date Dec. 31, 2016    
Unrecognized tax benefits $ 9,412,000 6,864,000 $ 5,793,000
Income tax, penalties and interest expense 0 $ 0 $ 0
Federal      
Operating Loss Carryforwards [Line Items]      
Net operating loss carryforwards 818,500,000    
Tax credit carryforwards 14,800,000    
Net operating loss carryforwards recognized through additional paid in capital, if realized 377,300,000    
Federal | Acquisitions      
Operating Loss Carryforwards [Line Items]      
Net operating loss carryforwards 62,400,000    
State      
Operating Loss Carryforwards [Line Items]      
Net operating loss carryforwards 552,200,000    
Tax credit carryforwards that do not expire 15,800,000    
Tax credit carryforwards that will expire beginning in 2024 5,700,000    
State | Acquisitions      
Operating Loss Carryforwards [Line Items]      
Net operating loss carryforwards 41,300,000    
Foreign      
Operating Loss Carryforwards [Line Items]      
Net operating loss carryforwards 8,200,000    
Foreign | Acquisitions      
Operating Loss Carryforwards [Line Items]      
Net operating loss carryforwards $ 3,800,000