Segments - Reconciliation of Assets from Segment to Consolidated (Details) - USD ($) $ in Millions	Dec. 31, 2020	Sep. 30, 2020
Segment Reporting, Asset Reconciling Item [Line Items]
Restricted cash	$ 0.0	$ 790.0
Goodwill and other intangible assets	2,974.4	2,925.0
Total assets	4,929.1	5,728.3
Operating Segments
Segment Reporting, Asset Reconciling Item [Line Items]
Tangible assets	1,837.7	1,906.5
Corporate
Segment Reporting, Asset Reconciling Item [Line Items]
Tangible assets	117.0	106.8
Americas | Operating Segments
Segment Reporting, Asset Reconciling Item [Line Items]
Tangible assets	1,124.2	1,238.0
International | Operating Segments
Segment Reporting, Asset Reconciling Item [Line Items]
Tangible assets	$ 713.5	$ 668.5