Pension And Other Postretirement Benefits (Components Of The Plans' Net Periodic Benefits Cost) (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Pension Plan      
Defined Benefit Plan Disclosure [Line Items]      
Service Cost [1] $ 5.3    
Interest cost [1] 12.5    
Expected return on assets (23.6)    
Amortization of prior service cost (0.9)    
Recognized actuarial loss 8.2    
Net Periodic Benefit Costs 1.5    
Settlement loss 0.0    
Total Net Periodic Benefits Cost 1.5    
Other Postretirement Benefits      
Defined Benefit Plan Disclosure [Line Items]      
Service Cost [1] 1.0    
Interest cost [1] 4.0    
Expected return on assets (17.4)    
Amortization of prior service cost 0.1    
Recognized actuarial loss (0.2)    
Net Periodic Benefit Costs (12.5)    
Settlement loss 0.0    
Total Net Periodic Benefits Cost $ (12.5)    
Predecessor | Pension Plan      
Defined Benefit Plan Disclosure [Line Items]      
Service Cost   $ 4.8 [1] $ 4.8
Interest cost   13.7 [1] 12.6
Expected return on assets   (23.8) (22.0)
Amortization of prior service cost   (1.0) (0.9)
Recognized actuarial loss   6.6 10.6
Net Periodic Benefit Costs   0.3 5.1
Settlement loss   0.0 12.4
Total Net Periodic Benefits Cost   0.3 17.5
Predecessor | Other Postretirement Benefits      
Defined Benefit Plan Disclosure [Line Items]      
Service Cost   1.1 [1] 1.5
Interest cost   4.6 [1] 4.9
Expected return on assets   (16.5) (13.5)
Amortization of prior service cost   0.1 0.1
Recognized actuarial loss   (0.1) 1.0
Net Periodic Benefit Costs   (10.8) (6.0)
Settlement loss   0.0 0.0
Total Net Periodic Benefits Cost   $ (10.8) $ (6.0)
[1] The change in benefit obligation for Pension Benefits represents the change in Projected Benefit Obligation while the change in benefit obligation for Other Postretirement Benefits represents the change in Accumulated Postretirement Benefit Obligation.