Nature of operations and summary of significant accounting policies (Cash and Cash Equivalents) (Details) $ in Thousands	Dec. 31, 2019 USD ($)
Accounting Policies [Abstract]
Cash held	$ 22,057

This item represents disclosure of all significant concentrations of credit risk or market risk arising from the subject financial instrument (as defined), whether from an individual counterparty or groups of counterparties.

No definition available.

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