Summary of significant accounting policies - Recently Issued Accounting Pronouncement (Details)	Jan. 01, 2020
ASU 2018-18
New Accounting pronouncements
Change in Accounting Principle, Accounting Standards Update, Adopted	true
ASU 2016-13
New Accounting pronouncements
Change in Accounting Principle, Accounting Standards Update, Adopted	true

Indicates (true false) whether accounting standards update was adopted.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22499-107794

Name:	us-gaap_ChangeInAccountingPrincipleAccountingStandardsUpdateAdopted
Namespace Prefix:	us-gaap_
Data Type:	xbrli:booleanItemType
Balance Type:	na
Period Type:	instant