Share-based Payments - Measurement of Fair Value of Share Options Granted (Details) - CAD ($)	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Share-Based Payment Arrangements [Abstract]
Weighted average fair market value per option (C$)	$ 0.88	$ 0.70
Risk free interest rate (%)	2.14%	0.74%
Expected volatility (based on actual historical volatility) (%)	49.45%	48.67%
Dividend rate	0.00%	0.00%
Expected forfeiture rate (non-executive employees) (%)	0.00%	0.00%
Suboptimal exercise factor	1.25	1.25

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 2018-01-01
-Paragraph 47
-Subparagraph a
-Clause i
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=2&date=2018-03-01&anchor=para_47_a_i&doctype=Standard
-URIDate 2018-03-16

+ 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

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_WeightedAverageSharePriceShareOptionsGranted
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	duration

- Definition

Expected Forfeiture Rate, Share Options Granted

+ References

No definition available.

+ Details

Name:	tga_ExpectedForfeitureRateShareOptionsGranted
Namespace Prefix:	tga_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Share-based payment arrangements [Abstract]

+ References

No definition available.

+ Details

Name:	tga_ShareBasedPaymentArrangementsAbstract
Namespace Prefix:	tga_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Suboptimal Exercise Factor

+ References

No definition available.

+ Details

Name:	tga_SuboptimalExerciseFactor
Namespace Prefix:	tga_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	duration