Receivables and allowance for expected credit losses (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020
Credit Loss [Abstract]
Accounts Receivable, Noncurrent, 90 Days or More Past Due, Still Accruing	$ 37.9	$ 43.9	$ 48.9

Amount of accounts receivable, classified as noncurrent, 90 days or more past due and still accruing.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 16
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919258-210447

Name:	us-gaap_AccountsReceivableNoncurrent90DaysOrMorePastDueStillAccruing
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant