Expected life.

No definition available.

Name:	alo_ExpectedLife
Namespace Prefix:	alo_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The expected volatility of the share price used to calculate the fair value of the share options granted. Expected volatility is a measure of the amount by which a price is expected to fluctuate during a period. The measure of volatility used in option pricing models is the annualised standard deviation of the continuously compounded rates of return on the share over a period of time.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 2
-IssueDate 2019-01-01
-Paragraph 47
-Subparagraph a
-Clause i
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=2&code=ifrs-tx-2019-en-r&anchor=para_47_a_i&doctype=Standard
-URIDate 2019-03-27

+ Details

Name:	ifrs-full_DescriptionOfExpectedVolatilityShareOptionsGranted
Namespace Prefix:	ifrs-full_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The implied yield currently available on zero-coupon government issues of the country in whose currency the exercise price for share options granted is expressed, with a remaining term equal to the expected term of the option being valued (based on the option's remaining contractual life and taking into account the effects of expected early exercise). [Refer: Government [member]]

+ References

+ Details

Name:	ifrs-full_DescriptionOfRiskFreeInterestRateShareOptionsGranted
Namespace Prefix:	ifrs-full_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table.

+ References

No definition available.

+ Details

Name:	ifrs-full_DisclosureOfBusinessCombinationsLineItems
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The percentage of an expected dividend used to calculate the fair value of share options granted.

+ References

+ Details

Name:	ifrs-full_ExpectedDividendAsPercentageShareOptionsGranted
Namespace Prefix:	ifrs-full_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	ifrs-full_BusinessCombinationsAxis=alo_RyePatchMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_ClassesOfFinancialInstrumentsAxis=alo_WarrantsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_RangeAxis=ifrs-full_BottomOfRangeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_RangeAxis=ifrs-full_TopOfRangeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Rye Patch Acquisition - Summary of Replacement Warrants (Details)		12 Months Ended
	May 25, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disclosure Of Business Combinations [Line Items]
Risk-free interest rate		1.50%	2.20%	1.20%
Annualized volatility		43.30%	47.40%	75.40%
Dividend rate		0.00%	0.00%	0.00%
Rye Patch \| Warrants
Disclosure Of Business Combinations [Line Items]
Risk-free interest rate	1.90%
Dividend rate	0.00%
Rye Patch \| Minimum \| Warrants
Disclosure Of Business Combinations [Line Items]
Expected life of warrants	2 months 12 days
Annualized volatility	25.90%
Rye Patch \| Maximum \| Warrants
Disclosure Of Business Combinations [Line Items]
Expected life of warrants	3 years 2 months 12 days
Annualized volatility	45.70%