Other current assets (Summary of Assets Held For Sale) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Other current assets
Beginning balance	$ 15,051	$ 15,051
Reclassified from (to) property, plant and equipment	(6,888)	4,071
Disposal	$ (8,163)	(4,071)
Ending balance		$ 15,051

Amount of assets held-for-sale that are not part of a disposal group, expected to be sold within a year or the normal operating cycle, if longer.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 15
-Paragraph 4
-Subparagraph (b)(2)
-URI http://asc.fasb.org/extlink&oid=121558832&loc=d3e400-110220

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