XML 56 R45.htm IDEA: XBRL DOCUMENT v3.8.0.1
Income Taxes - Textual (Details) - USD ($)
$ in Millions
3 Months Ended 12 Months Ended
Mar. 31, 2018
Mar. 31, 2017
Dec. 31, 2015
Dec. 31, 2017
Income Tax Contingency [Line Items]        
Provision for income tax expense $ 30.0 $ 39.7    
Net deferred tax assets 68.5      
Valuation allowance 36.2      
Additional tax benefits due to approval of accounting method change 51.3   $ 39.0  
Gross unrecognized tax benefits 1.1     $ 0.3
Gross unrecognized tax benefits that would impact effective tax rate if recognized 1.1     $ 0.3
Amount of decrease in unrecognized tax benefit to be released 0.2      
State and Local Jurisdiction [Member]        
Income Tax Contingency [Line Items]        
Operating Loss Carryforwards $ 75.6