Post Employment Benefit Plans (Details)
$ in Millions
12 Months Ended
Sep. 11, 2014
Dec. 31, 2017
USD ($)
plan
Dec. 31, 2016
USD ($)
Retirement Benefits [Abstract]      
Defined contribution plan, number of plans | plan   1  
Portion of contributions charged to income   $ 3.0 $ 2.7
Benefits plan vesting percentage 100.00%    
Benefit contributions accrued   $ 0.1