Debt and Other Financing Arrangements - Corporate Credit Agreement (2012 through 2017) (Details) - USD ($) $ in Millions	3 Months Ended					12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2013	Oct. 02, 2017	Sep. 30, 2013	Dec. 31, 2012
Line of Credit Facility [Line Items]
Loss (Gain) on Extinguishment of Debt	$ 3.2	$ 4.8	$ 11.4	$ 5.2	$ 2.4	$ (3.2)	$ (19.0)	$ (20.9)
Proceeds from Issuance of Long-term Debt						943.0	$ 635.0	$ 0.0
Tranche B Term Loan due 2020 [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Face Amount										$ 315.8	$ 540.0
Proceeds from Issuance of Long-term Debt									$ 529.8
Issuance of Long-Term Debt, Original Issue Discount									0.75%
Tranche B Term Loan due 2020 [Member] | London Interbank Offered Rate (LIBOR) [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate							3.00%
Standby Letters of Credit [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity												$ 30.0
Bridge Loan [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity												$ 25.0
Line of Credit [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		150.0					$ 150.0
Revolving Credit Facility And Tranche B Term Loan due 2020 [Member]
Line of Credit Facility [Line Items]
Loss (Gain) on Extinguishment of Debt	$ 3.2
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Loss (Gain) on Extinguishment of Debt				$ 1.7
Tranche B Term Loan [Member]
Line of Credit Facility [Line Items]
Loss (Gain) on Extinguishment of Debt						$ 2.6
Tranche B Term Loan due 2020 [Member]
Line of Credit Facility [Line Items]
Loss (Gain) on Extinguishment of Debt		2.2
Extinguishment of Debt, Amount		$ 208.0
London Interbank Offered Rate (LIBOR) [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		3.50%					3.50%			3.75%
Debt Instrument, Basis Spread on Variable Rate						1.00%	1.00%
London Interbank Offered Rate (LIBOR) [Member] | Tranche B Term Loan due 2020 [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate							1.00%
London Interbank Offered Rate (LIBOR) [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		3.00%					3.00%			1.00%
London Interbank Offered Rate (LIBOR) [Member] | Minimum [Member] | Tranche B Term Loan [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		1.00%					1.00%
London Interbank Offered Rate (LIBOR) [Member] | Maximum [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		3.50%					3.50%
Federal Funds Rate [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate							0.50%
Federal Funds Rate [Member] | Tranche B Term Loan due 2020 [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate							0.50%
Base Rate [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		2.50%					2.50%			2.75%
Base Rate [Member] | Tranche B Term Loan due 2020 [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate							2.00%
Base Rate [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		2.00%					2.00%
Base Rate [Member] | Maximum [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		2.50%					2.50%