Quarterly report pursuant to Section 13 or 15(d)

Income Taxes (Details)

v3.7.0.1
Income Taxes (Details) - USD ($)
$ in Thousands
3 Months Ended 6 Months Ended 12 Months Ended
Jun. 30, 2017
Jun. 30, 2016
Jun. 30, 2017
Jun. 30, 2016
Dec. 31, 2017
Dec. 31, 2016
Income Tax Disclosure [Abstract]            
Income tax expense $ 119,513 $ 106,310 $ 233,486 $ 214,552    
Income Taxes [Line Items]            
Effective income tax rate percent 37.20% 37.80% 36.30% 38.20%    
Valuation allowance $ 44,022   $ 44,022     $ 47,682
Forecast            
Income Taxes [Line Items]            
Effective income tax rate percent         37.40%