Supplementary Financial Information - Schedule of Other Non-Current Assets (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Offsetting [Abstract]
Right of use asset	$ 68.1	$ 39.8
Other	4.4	2.4
Total other non-current assets	$ 72.5	$ 42.2

Amount of lessee's right to use underlying asset under operating lease.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 45
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123391704&loc=SL77918627-209977

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