Contingencies (Narrative) (Details) $ in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2019 AUD ($) Mt / yr	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Facility B [Member]
Loss Contingencies [Line Items]
Guarantee Obligations Available	$ 130.0
Company guarantees	68.0
Rail Links Litigation Versus Aurizon [Member]
Loss Contingencies [Line Items]
Litigation congtingency, estimate of annual payment	$ 2.3
Litigation contingency, rail access entitlement (in MMtpa) | Mt / yr	1.5
Litigation congtingency, term of deed	233 months
Litigation contingency, term of rail access entitlement	20 years
Loss contingency accrual		$ 5.3	$ 3.5