Net Loss per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Numerator:
Net loss	$ (42,915)	$ (28,260)	$ (100,108)	$ (38,065)
Net (income) loss attributable to non-controlling interests		50		69
Accretion of beneficial conversion feature on Series A preferred shares			(12,006)
Net loss attributable to common shareholders of Biohaven Pharmaceutical Holding Company Ltd.	$ (42,915)	$ (28,210)	$ (112,114)	$ (37,996)
Denominator:
Weighted average common shares outstanding-basic and diluted	35,930,698	13,050,446	25,102,920	12,447,153
Net loss per share attributable to common shareholders of Biohaven Pharmaceutical Holding Company Ltd.-basic and diluted	$ (1.19)	$ (2.16)	$ (4.47)	$ (3.05)