Income Taxes - Narrative (Details) - USD ($)
$ in Thousands
3 Months Ended
Mar. 31, 2018
Mar. 31, 2017
Income Tax Expense Benefit [Line Items]    
Effective tax rate 5.00% (4.50%)
Income tax expense (benefit) $ (2,445) $ 2,358
Without Adoption (ASC 605)    
Income Tax Expense Benefit [Line Items]    
Effective tax rate (4.30%)  
Income tax expense (benefit) $ 3,300