Business Segment Information - Long-lived Assets (Details) - USD ($) $ in Millions	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Segment Information
Long-lived assets, net	$ 166.3	$ 145.0	$ 124.4
United States
Segment Information
Long-lived assets, net	148.2	128.4	106.7
United Kingdom
Segment Information
Long-lived assets, net	7.1	5.9	5.7
Other foreign countries
Segment Information
Long-lived assets, net	$ 11.0	$ 10.7	$ 12.0

Long-lived assets other than financial instruments, long-term customer relationships of a financial institution, mortgage and other servicing rights, deferred policy acquisition costs, and deferred tax assets.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 41
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9038-108599

Name:	us-gaap_NoncurrentAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant