Quarterly report pursuant to Section 13 or 15(d)

Income Taxes (Details)

v3.8.0.1
Income Taxes (Details) - USD ($)
$ in Thousands
3 Months Ended 12 Months Ended
Mar. 31, 2018
Mar. 31, 2017
Dec. 31, 2018
Dec. 31, 2017
Income Tax Disclosure [Abstract]        
Income tax expense $ 80,249 $ 113,973    
Income Taxes [Line Items]        
Effective income tax rate percent 21.70% 35.50%    
Valuation allowance $ 52,459     $ 52,883
Forecast        
Income Taxes [Line Items]        
Effective income tax rate percent     24.00%