SHARE CAPITAL AND SHARE-BASED PAYMENTS - Valuation Assumptions (Details)	12 Months Ended
Dec. 31, 2020 year $ / shares	Dec. 31, 2019 year $ / shares
Share-Based Payment Arrangements [Abstract]
Estimated forfeiture rate (%)	3.00%	3.00%
Expected dividend yield (%)	0.00%	0.00%
Risk-free interest rate (%)	1.31%	1.78%
Expected life (years) \| year	4.2	4.2
Expected volatility (%)	45.80%	45.80%
Weighted average share price (C$) \| $ / shares	$ 26.12	$ 16.81

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.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 2
-IssueDate 2020-01-01
-Paragraph 47
-Subparagraph a
-Clause i
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=2&code=ifrs-tx-2020-en-r&anchor=para_47_a_i&doctype=Standard
-URIDate 2020-01-01

+ Details

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

- Definition

The option life of share options granted.

+ References

+ Details

Name:	ifrs-full_DescriptionOfOptionLifeShareOptionsGranted
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:decimalItemType
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

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

- Definition

The weighted average share price used as input to the option pricing model to calculate the fair value of share options granted. [Refer: Option pricing model [member]; Weighted average [member]]

+ References

+ Details

Name:	ifrs-full_WeightedAverageSharePriceShareOptionsGranted2019
Namespace Prefix:	ifrs-full_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Forfeiture Rate, Share Options Granted

+ References

No definition available.

+ Details

Name:	ssrm_ForfeitureRateShareOptionsGranted
Namespace Prefix:	ssrm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Share-Based Payment Arrangements [Abstract]

+ References

No definition available.

+ Details

Name:	ssrm_ShareBasedPaymentArrangementsAbstract
Namespace Prefix:	ssrm_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration