Net Loss Per Share - Calculation of Basic and Diluted Net Loss per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Numerator:
Net loss	$ (70,492)	$ (97,032)
Denominator:
Common shares outstanding—basic (shares)	68,206,879	39,375,944
Common shares outstanding—diluted (shares)	68,206,879	39,375,944
Net loss per share attributable to common shareholders of Biohaven Pharmaceutical Holding Company Ltd. - basic (in dollars per share)	$ (1.03)	$ (2.46)
Net loss per share attributable to common shareholders of Biohaven Pharmaceutical Holding Company Ltd. - diluted (in dollars per share)	$ (1.03)	$ (2.46)