v3.8.0.1
Income Taxes - Narrative (Details) - USD ($)
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Income Tax Disclosure [Abstract]      
Provisional tax benefit for impact of 2017 Tax Act $ 13,500,000    
Percent reduction of effective tax rate due to Qualified Domestic Production Activities 3.10% 3.40% 1.20%
Income tax payments $ 30,000,000 $ 6,700,000 $ 14,000,000
Reserve for uncertain tax positions $ 0 $ 0