Shareholders' Equity and Long-Term Incentive Compensation - AOCI (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Oct. 01, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Components of accumulated other comprehensive income, net of tax [Roll Forward]
Beginning Balance			$ 191.6
Other comprehensive Income (loss), net			15.0	$ (48.2)	$ (133.9)
Ending Balance			314.7	191.6
Other Expense
Accumulated Other Comprehensive income
Gain on derivative			2.7
Accum. Other Comprehensive Income
Components of accumulated other comprehensive income, net of tax [Roll Forward]
Beginning Balance		$ 283.3	235.1	283.3
Other comprehensive income before reclassifications			19.1	(10.8)
Amounts reclassified from accumulated other comprehensive income			(4.1)	(37.4)
Other comprehensive Income (loss), net			15.0	(48.2)	(133.9)
Ending Balance			250.1	235.1	283.3
Foreign Currency Translation Adjustment
Components of accumulated other comprehensive income, net of tax [Roll Forward]
Beginning Balance		280.6	229.7	280.6
Other comprehensive income before reclassifications			0.5	(11.9)
Amounts reclassified from accumulated other comprehensive income			0.0	(39.0)
Other comprehensive Income (loss), net			0.5	(50.9)
Ending Balance			230.2	229.7	280.6
Foreign Currency Translation Adjustment | Dry Cooling Business | Disposal Group, Disposed of by Sale, Not Discontinued Operations | Gain on Sale of Dry Cooling Business
Components of accumulated other comprehensive income, net of tax [Roll Forward]
Amounts reclassified from accumulated other comprehensive income		(40.4)
Net Unrealized Losses on Qualifying Cash Flow Hedges
Accumulated Other Comprehensive income
Pension and postretirement liability adjustment and other, tax provision benefit			0.5	(0.9)	0.8
Components of accumulated other comprehensive income, net of tax [Roll Forward]
Beginning Balance		(1.8)	1.5	(1.8)
Other comprehensive income before reclassifications			2.3	1.1
Amounts reclassified from accumulated other comprehensive income			(3.0)	2.2
Other comprehensive Income (loss), net			(0.7)	3.3
Ending Balance			0.8	1.5	(1.8)
Pension and Postretirement Liability Adjustment and Other
Accumulated Other Comprehensive income
Pension and postretirement liability adjustment and other, tax provision benefit			12.5	2.7	3.1
Components of accumulated other comprehensive income, net of tax [Roll Forward]
Beginning Balance		$ 4.5	3.9	4.5
Other comprehensive income before reclassifications			16.3	0.0
Amounts reclassified from accumulated other comprehensive income			(1.1)	(0.6)
Other comprehensive Income (loss), net			15.2	(0.6)
Ending Balance			19.1	$ 3.9	$ 4.5
U.S. Postretirement Plan (“OPEB”)
Accumulated Other Comprehensive income
Plan amendment	$ (26.8)		$ 26.8