Leases - Finance leases (Details)	12 Months Ended
Dec. 31, 2020 item
Operating leases:
Number of finance leases	1
Minimum
Operating leases:
Finance lease, remaining lease term	1 year
Maximum
Operating leases:
Finance lease, remaining lease term	17 years

Remaining lease term of finance lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=121609121&loc=SL77918673-209980

Name:	us-gaap_LesseeFinanceLeaseRemainingLeaseTerm
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant