Long-Term Debt and Capital Leases - Debt Agreements (Details) $ in Millions						3 Months Ended			9 Months Ended		12 Months Ended
	Jul. 17, 2017 USD ($)	May 31, 2017 USD ($)	Mar. 20, 2017 USD ($)	Aug. 19, 2016 USD ($)	May 11, 2016 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Dec. 31, 2016 item
Long-Term Debt and Capital Leases
Loss on early extinguishment of debt						$ 26.1		$ 28.1	$ 32.1	$ 30.6
Term B Loans
Long-Term Debt and Capital Leases
Repayments of long-term debt				$ 1,825.0
Loss on early extinguishment of debt						6.3		$ 32.1
Term B Loans | Eighth Amendment to Senior Secured Credit Facilities
Long-Term Debt and Capital Leases
Outstanding balance	$ 2,280.0
Face amount	$ 230.5
Term B Loans | Eighth Amendment to Senior Secured Credit Facilities | LIBOR rate
Long-Term Debt and Capital Leases
Basis spread on variable rate (as a percent)	3.25%
Term B Loans | Eighth Amendment to Senior Secured Credit Facilities | Alternate base rate
Long-Term Debt and Capital Leases
Basis spread on variable rate (as a percent)	2.25%
Term B Loans | Sixth Amendment to Senior Secured Credit Facilities
Long-Term Debt and Capital Leases
Term of debt instrument				7 years
Period of time after debt instrument term for which a conditional maturity clause becomes effective related to refinancing existing debt				91 days
Funding acquisition and repayment of long-term debt				$ 240.0
Face amount				$ 2,065.0
Term B Loans | Sixth Amendment to Senior Secured Credit Facilities | LIBOR rate
Long-Term Debt and Capital Leases
Basis spread on variable rate (as a percent)				3.50%
Variable interest rate floor (as a percent)				1.00%
Term B Loans | Sixth Amendment to Senior Secured Credit Facilities | Alternate base rate
Long-Term Debt and Capital Leases
Basis spread on variable rate (as a percent)				2.50%
Term B Loans | Fifth Amendment to Senior Secured Credit Facilities
Long-Term Debt and Capital Leases
Face amount					$ 432.5
Term B Loans | Fifth Amendment to Senior Secured Credit Facilities | LIBOR rate
Long-Term Debt and Capital Leases
Basis spread on variable rate (as a percent)					3.50%
Variable interest rate floor (as a percent)					1.00%
Term B Loans | Fifth Amendment to Senior Secured Credit Facilities | Alternate base rate
Long-Term Debt and Capital Leases
Basis spread on variable rate (as a percent)					2.50%
Term B-1 Loans
Long-Term Debt and Capital Leases
Repayments of long-term debt					$ 382.5
Term B-1 Loans | LIBOR rate
Long-Term Debt and Capital Leases
Basis spread on variable rate (as a percent)					3.00%
Variable interest rate floor (as a percent)					0.75%
Term B-1 Loans | Alternate base rate
Long-Term Debt and Capital Leases
Basis spread on variable rate (as a percent)					2.00%
Revolving Credit Facility
Long-Term Debt and Capital Leases
Borrowings available						$ 300.0			$ 300.0
Revolving Credit Facility | Eighth Amendment to Senior Secured Credit Facilities
Long-Term Debt and Capital Leases
Additional borrowing capacity	$ 100.0
Outstanding balance	$ 300.0
Revolving Credit Facility | Eighth Amendment to Senior Secured Credit Facilities | LIBOR rate
Long-Term Debt and Capital Leases
Basis spread on variable rate (as a percent)	3.00%
Revolving Credit Facility | Eighth Amendment to Senior Secured Credit Facilities | Alternate base rate
Long-Term Debt and Capital Leases
Basis spread on variable rate (as a percent)	2.00%
Revolving Credit Facility | Seventh Amendment To Senior Secured Credit Facilities
Long-Term Debt and Capital Leases
Borrowings available		$ 200.0
Additional borrowing capacity		$ 300.0
Loss on early extinguishment of debt							$ 1.0
Revolving Credit Facility | Seventh Amendment To Senior Secured Credit Facilities | LIBOR rate
Long-Term Debt and Capital Leases
Basis spread on variable rate (as a percent)		3.00%
Revolving Credit Facility | Seventh Amendment To Senior Secured Credit Facilities | Alternate base rate
Long-Term Debt and Capital Leases
Basis spread on variable rate (as a percent)		2.00%
Senior Notes
Long-Term Debt and Capital Leases
Repayments of long-term debt			$ 95.1
Repayments of long term debt, principal amount	$ 729.9
Interest rate (as a percent)	10.25%		10.25%
Loss on early extinguishment of debt	$ 19.8		$ 5.0
Prepayment fees	18.7
Accrued interest paid	37.6		1.7
Payment of call premium			$ 4.9
Outstanding balance	$ 180.0
Senior Subordinated Notes
Long-Term Debt and Capital Leases
Interest rate (as a percent)											13.38%
Number of redemption payments made | item											2