Consolidated Statements of Member's Interest - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance, Stockholders' Equity			$ 1,056.5
Beginning balance Total Member's Interest	$ 2,745.3	$ 1,569.3
Net Income	333.5	337.2	576.4
Other Comprehensive (Loss) Income, Net of Tax:
Derivative Instruments	(8.9)	(1.6)	(4.9)
Pension and Postretirement Benefit Plans	13.6	(32.4)	8.8
Currency Translation Adjustment	12.4	(24.5)	44.9
Repurchase of Common Stock			(58.4)
Pre-2017 Excess Tax Benefit			39.1
Dividends Declared			(93.1)
NACP Combination		1,112.2
Contributions	17.6	27.0	1.2
Recognition of Stock-Based Compensation			(1.2)
Distributions of Membership Interest	(256.9)	(241.9)
Ending balance Total Member's Interest	2,856.6	2,745.3	1,569.3
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance, Stockholders' Equity	0.0	0.0	3.1
Other Comprehensive (Loss) Income, Net of Tax:
Repurchase of Common Stock			0.0
Formation of Partnership			(3.1)
Ending balance, Stockholders' Equity	0.0	0.0	0.0
Capital in Excess of Par Value
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance, Stockholders' Equity	0.0	0.0	1,709.0
Other Comprehensive (Loss) Income, Net of Tax:
Repurchase of Common Stock			(24.2)
Recognition of Stock-Based Compensation			(1.2)
Formation of Partnership			(1,683.6)
Ending balance, Stockholders' Equity	0.0	0.0	0.0
(Accumulated Deficit) Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance, Stockholders' Equity	0.0	0.0	(268.0)
Net Income			300.2
Other Comprehensive (Loss) Income, Net of Tax:
Repurchase of Common Stock			(34.2)
Pre-2017 Excess Tax Benefit			39.1
Dividends Declared			(93.1)
Formation of Partnership			56.0
Ending balance, Stockholders' Equity	0.0	0.0	0.0
Member's Interest
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance Total Member's Interest	3,142.6	1,908.1
Net Income	333.5	337.2	276.2
Other Comprehensive (Loss) Income, Net of Tax:
NACP Combination		1,112.2
Contributions	17.6	27.0	1.2
Formation of Partnership			1,630.7
Distributions of Membership Interest	(256.9)	(241.9)
Ending balance Total Member's Interest	3,236.8	3,142.6	1,908.1
Accumulated Other Comprehensive (Loss) Income
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance, Stockholders' Equity			(387.6)
Beginning balance Total Member's Interest	(397.3)	(338.8)
Other Comprehensive (Loss) Income, Net of Tax:
Derivative Instruments	(8.9)	(1.6)	(4.9)
Pension and Postretirement Benefit Plans	13.6	(32.4)	8.8
Currency Translation Adjustment	12.4	(24.5)	44.9
Ending balance Total Member's Interest	$ (380.2)	$ (397.3)	$ (338.8)