Related party transactions (Summary of Related Party Outstanding Balances) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Related Party Transaction [Line Items]
Miscellaneous	$ 95,814	$ 99,049
Axionlog Distribution B.V.
Related Party Transaction [Line Items]
Accounts and notes receivable, net	177	860
Other receivables	2,201	1,676
Miscellaneous	3,719	2,963
Accounts payable	$ (8,747)	$ (14,984)

Amount for accounts payable to related parties.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant