Share Capital - Additional Information (Detail)										1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 16, 2021 USD ($) shares	Aug. 16, 2021 USD ($) shares	Jul. 01, 2021 USD ($) shares	Mar. 22, 2021 USD ($) shares	Mar. 15, 2021 USD ($) shares	Feb. 23, 2021 USD ($) $ / shares shares	Feb. 22, 2021 USD ($) shares	Feb. 08, 2021 USD ($) $ / shares shares	Apr. 23, 2019 USD ($)	Jun. 30, 2018	Sep. 30, 2021 USD ($) shares	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($) Dispensary shares	Sep. 30, 2020 USD ($)	Dec. 31, 2020 USD ($) shares
Reduction in contingent liability | $													$ 662,027	$ (425,424)
Business combination, contigent liability | $											$ 61,853,000		61,853,000
Current liabilities | $											165,301,783		165,301,783		$ 119,288,435
Contingent consideration | $											(249,078)	$ 442,991	(662,027)	$ 425,426
Integral Associates LLC [Member]
Reduction in contingent liability | $				$ 7,750,000
Business combination, contigent liability | $											14,850,000		14,850,000		$ 27,100,000
Non current liability | $											4,950,000		$ 4,950,000
GTI New Jersey, LLC [Member]
Issuance of shares under business combinations and investments													0		2,000,000
Business acquisition, equity interest issuable fair value | $															$ 2,000,000
Dharma Pharmaceuticals LLC [Member]
Business combination, contigent liability | $		$ 45,900,000									45,872,665		$ 45,872,665
Non current liability | $		$ 19,800,000
Current liabilities | $											19,883,434		$ 19,883,434
Dharma Pharmaceuticals LLC [Member] | Maximum [Member]
Retail dispensary | Dispensary													5
Restricted Stock Units (RSUs) [Member]
Cost Not yet Recognized, Amount | $											$ 24,203,212		$ 24,203,212
Cost Not yet Recognized, Period for Recognition													2 years 18 days
Multiple Voting Shares [Member]
Conversion of Stock, Shares Issued													(635)
Common Stock, Shares, Outstanding											39,654		39,654		40,289
Issuance of shares under business combinations and investments													0
Multiple Voting Shares [Member] | Conversion Of Multiple Voting Shares [member]
Conversion Of Stock, Shares Converted													635
Conversion of Stock, Shares Issued													635
Voting Rights													100
Subordinate Voting Shares [Member]
Conversion of Stock, Shares Issued													1,763,500
Common Stock, Shares, Outstanding											194,383,883		194,383,883		178,113,221
Issuance of shares under business combinations and investments													7,290,180
Stock issued during period, shares, new issues													4,693,991
Subordinate Voting Shares [Member] | February Nine Two Thousand Twenty One
Stock issued during period, shares, new issues								3,122,074
Shares issued, price per share | $ / shares								$ 32.03
Stock issued during period, value, issued for services | $								$ 100,000,030
Subordinate Voting Shares [Member] | February Twenty Three Two Thousand Twenty One
Stock issued during period, shares, new issues						1,571,917
Shares issued, price per share | $ / shares						$ 35.50
Stock issued during period, value, issued for services | $						$ 55,803,054
Professional Fees | $						$ 304,944
Subordinate Voting Shares [Member] | Integral Associates LLC [Member]
Issuance of shares under business combinations and investments				412,744
Issuance of shares under business combinations and investments, value | $				$ 12,672,681
Business acquisition, equity interest measurement loss | $				$ 8,172,681
Subordinate Voting Shares [Member] | Success Holdings [Member]
Issuance of shares under business combinations and investments							146,315
Issuance of shares under business combinations and investments, value | $							$ 1,825,597
Shares forfeited							780
Shares forfieted value | $							$ 9,732
Subordinate Voting Shares [Member] | GTI New Jersey, LLC [Member]
Issuance of shares under business combinations and investments	36,947				30,414
Issuance of shares under business combinations and investments, value | $	$ 939,538				$ 1,038,307				$ 3,000,000
Subordinate Voting Shares [Member] | Dharma Pharmaceuticals LLC [Member]
Issuance of shares under business combinations and investments		199,993	2,298,779
Issuance of shares under business combinations and investments, value | $		$ 5,949,078	$ 75,900,000
Subordinate Voting Shares [Member] | Dharma Pharmaceuticals LLC [Member] | Maximum [Member]
Contingent consideration | $													$ 65,000,000.0
Subordinate Voting Shares [Member] | GTII Stock and Incentive Plan [Member]
Percentage of maximum number of shares issued under the plan										10.00%
Subordinate Voting Shares [Member] | Conversion Of Multiple Voting Shares [member]
Conversion of Stock, Shares Issued													63,500
Shares Available For Conversion											3,965,400		3,965,400
Subordinate Voting Shares [Member] | Conversion Of Super Voting Shares [member]
Conversion of Stock, Shares Issued													1,700,000
Super Voting Shares [Member]
Conversion of Stock, Shares Issued													(17,000)
Common Stock, Shares, Outstanding											295,031		295,031		312,031
Issuance of shares under business combinations and investments													0
Super Voting Shares [Member] | Conversion Of Super Voting Shares [member]
Conversion Of Stock, Shares Converted													17,000
Conversion of Stock, Shares Issued													17,000
Voting Rights													1,000
Shares Available For Conversion											29,503,100		29,503,100