Notes Payable and Indebtedness - Summary (Details) $ in Millions	6 Months Ended
	Jun. 30, 2021 USD ($)	Dec. 31, 2020 USD ($)		Feb. 08, 2019
Debt Maturing Within One Year:
Principal Amount	$ 28.1	$ 25.3
Debt Issuance Costs and Discount	0.0	0.0
Carrying Value	28.1	25.3
Debt Maturing After One Year:
Principal Amount	3,638.9	3,355.7
Debt Issuance Costs and Discount	93.1	99.9
Carrying Value	3,545.8	3,255.8	[1]
Total debt
Principal Amount	3,667.0	3,381.0
Debt Issuance Costs and Discount	93.1	99.9
Carrying Value	3,573.9	3,281.1
New Term Loan Facility | Line of Credit
Debt Maturing After One Year:
Principal Amount	2,768.9	2,485.7
Debt Issuance Costs and Discount	72.2	77.1
Carrying Value	2,696.7	2,408.6
New Term Loan Facility | Line of Credit | Secured Debt
Debt Maturing Within One Year:
Principal Amount	28.1	25.3
Debt Issuance Costs and Discount	0.0	0.0
Carrying Value	28.1	25.3
New Revolving Facility | Line of Credit | Revolving Credit Facility
Debt Maturing After One Year:
Principal Amount	0.0	0.0
Debt Issuance Costs and Discount	0.0	0.0
Carrying Value	$ 0.0	0.0
Total debt
Maximum ratio of first lien net indebtedness to consolidated EBITDA	6.75
Applicable threshold for maximum ratio of first lien net indebtedness to consolidated EBITDA (as a percent)	35.00%
6.875% New Senior Secured Notes | Secured Debt
Debt Maturing After One Year:
Principal Amount	$ 420.0	420.0
Debt Issuance Costs and Discount	7.5	8.2
Carrying Value	412.5	411.8
Total debt
Interest rate on debt instrument (as a percent)				6.875%
10.250% New Senior Unsecured Notes | Unsecured Debt Excluding Current Maturities
Debt Maturing After One Year:
Principal Amount	450.0	450.0
Debt Issuance Costs and Discount	13.4	14.6
Carrying Value	$ 436.6	$ 435.4
10.250% New Senior Unsecured Notes | Unsecured Debt
Total debt
Interest rate on debt instrument (as a percent)				10.25%

[1] See discussion in Note 1 - Basis of Presentation for further detail regarding the elimination of the International lag reporting.