Repurchase of common stock - Narrative (Details) - USD ($)	Jun. 30, 2020	May 08, 2019
Equity [Abstract]
Amount authorized under share repurchase program		$ 25,000,000.0
Remaining authorized repurchase amount	$ 17,100,000

Amount remaining of a stock repurchase plan authorized.

No definition available.

Name:	us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant