Taxes - Summary of Operating Loss and Capital Loss Carryforwards (Details) - USD ($)	3 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Tax Credit Carryforward [Line Items]
Operating loss carryforwards		$ 159,200,000
Unrecognized tax benefits	$ 0	0
Impairment of taxes receivable	(1,400,000)
Colombia
Tax Credit Carryforward [Line Items]
Credit carryforward		3,300,000
Internal Revenue Service (IRS)
Tax Credit Carryforward [Line Items]
Operating loss carryforwards	50,500,000	22,700,000
Canada Revenue Agency
Tax Credit Carryforward [Line Items]
Operating loss carryforwards	31,500,000	27,100,000
Canada Revenue Agency | Capital Loss Carryforward
Tax Credit Carryforward [Line Items]
Credit carryforward	197,500,000	242,400,000
Colombian Tax and Customs National Authority
Tax Credit Carryforward [Line Items]
Operating loss carryforwards	140,500,000	99,000,000.0
Operating loss carryforwards, not subject to limitations			$ 75,400,000
Operating loss carryforwards, subject to limitations			$ 83,800,000
Colombian Tax and Customs National Authority | Capital Loss Carryforward
Tax Credit Carryforward [Line Items]
Credit carryforward	$ 1,500,000	$ 2,200,000