AMAK Asset Retirement Obligations - Narrative (Details) - AMAK - SAR (ر.س) ر.س in Thousands	9 Months Ended	12 Months Ended
Sep. 30, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2012
Schedule of Equity Method Investments [Line Items]
ARO recorded for deferred mine closure costs				ر.س 12,843
Amortization expense	ر.س 362	ر.س 541	ر.س 745

Amount of asset retirement obligations incurred during the period.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849

Name:	us-gaap_AssetRetirementObligationLiabilitiesIncurred
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration