Other assets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Other assets
Deferred debt financing fees	$ 8,901
Other receivables and deposits long term	824	$ 484
Total other assets	$ 9,725	$ 484

Amount of noncurrent assets classified as other.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.17)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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