Stock-Based Compensation - Schedule of Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Original Stock Option Plan [Member]
Stock options
Shares, Granted	0
Downstream Merger [Member] | Original Stock Option Plan [Member]
Stock options
Shares, Beginning Balance	592,594
Shares, Allocated to Tilray	143,794
Shares, Exercised	(25,751)
Shares, Forfeited	(9,527)
Shares, Cancelled	(8,267)
Shares, Converted with Downstream Merger	(692,843)
Shares, Ending Balance		592,594
Weighted-average exercise price
Weighted-average exercise price, Beginning Balance	$ 4.14
Weighted-average exercise price, Allocated to Tilray	4.21
Weighted-average exercise price, Exercised	3.95
Weighted-average exercise price, Forfeited	4.25
Weighted-average exercise price, Cancelled	3.46
Weighted-average exercise price, Converted with Downstream Merger	$ 4.22
Weighted-average exercise price, Ending Balance		$ 4.14
Weighted-average remaining contractual term (years)
Weighted-average remaining contractual term		8 years 1 month 6 days
Aggregate intrinsic value
Aggregate intrinsic value	$ 989
Aggregate intrinsic value		$ 989
Time-based Stock Options [Member] | 2018 Equity Incentive Plan [Member]
Stock options
Shares, Beginning Balance	6,015,791
Shares, Granted	10,000
Shares, Exercised	(621,363)
Shares, Forfeited	(91,048)
Shares, Cancelled	(6,250)
Shares, Ending Balance	5,307,130	6,015,791
Shares, Vested and expected to vest	5,072,605
Shares, Vested and exercisable	2,512,513
Weighted-average exercise price
Weighted-average exercise price, Beginning Balance	$ 13.54
Weighted-average exercise price, Granted	70.25
Weighted-average exercise price, Exercised	7.76
Weighted-average exercise price, Forfeited	30.16
Weighted-average exercise price, Cancelled	7.76
Weighted-average exercise price, Ending Balance	14.04	$ 13.54
Weighted-average exercise price, Vested and expected to vest	13.80
Weighted-average exercise price, Vested and exercisable	$ 11.91
Weighted-average remaining contractual term (years)
Weighted-average remaining contractual term	8 years 4 months 24 days	9 years 4 months 24 days
Weighted-average remaining contractual term, Vested and expected to vest	8 years 4 months 24 days
Weighted-average remaining contractual term, Vested and exercisable	8 years 4 months 24 days
Aggregate intrinsic value
Aggregate intrinsic value	$ 342,916
Aggregate intrinsic value	44,297	$ 342,916
Aggregate intrinsic value, Vested and expected to vest	42,537
Aggregate intrinsic value, Vested and exercisable	$ 21,840
Time-based Stock Options [Member] | Downstream Merger [Member] | 2018 Equity Incentive Plan [Member]
Stock options
Shares, Exercised	(107,359)
Shares, Cancelled	(13,068)
Shares, Ending Balance	3,014,004
Shares, Vested and expected to vest	2,992,598
Shares, Vested and exercisable	2,733,170
Shares, Assumed on Downstream Merger	3,134,431
Weighted-average exercise price
Weighted-average exercise price, Exercised	$ 1.81
Weighted-average exercise price, Cancelled	9.04
Weighted-average exercise price, Ending Balance	3.04
Weighted-average exercise price, Vested and expected to vest	2.98
Weighted-average exercise price, Vested and exercisable	2.77
Weighted-average exercise price, Assumed on Downstream Merger	$ 2.99
Weighted-average remaining contractual term (years)
Weighted-average remaining contractual term	5 years 9 months 18 days
Weighted-average remaining contractual term, Vested and expected to vest	5 years 9 months 18 days
Weighted-average remaining contractual term, Vested and exercisable	5 years 6 months
Aggregate intrinsic value
Aggregate intrinsic value	$ 44,108
Aggregate intrinsic value, Vested and expected to vest	43,717
Aggregate intrinsic value, Vested and exercisable	$ 40,423
Performance-based Stock Options [Member] | 2018 Equity Incentive Plan [Member]
Stock options
Shares, Beginning Balance	600,000
Shares, Exercised	(80,000)
Shares, Ending Balance	520,000	600,000
Shares, Vested and expected to vest	520,000
Shares, Vested and exercisable	520,000
Weighted-average exercise price
Weighted-average exercise price, Beginning Balance	$ 7.76
Weighted-average exercise price, Exercised	7.76
Weighted-average exercise price, Ending Balance	7.76	$ 7.76
Weighted-average exercise price, Vested and expected to vest	7.76
Weighted-average exercise price, Vested and exercisable	$ 7.76
Weighted-average remaining contractual term (years)
Weighted-average remaining contractual term	8 years 4 months 24 days	9 years 4 months 24 days
Weighted-average remaining contractual term, Vested and expected to vest	8 years 4 months 24 days
Weighted-average remaining contractual term, Vested and exercisable	8 years 4 months 24 days
Aggregate intrinsic value
Aggregate intrinsic value	$ 37,668
Aggregate intrinsic value	4,872	$ 37,668
Aggregate intrinsic value, Vested and expected to vest	4,872
Aggregate intrinsic value, Vested and exercisable	$ 4,872