Net Loss Per Share - Calculation of Basic and Diluted Net Loss per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Numerator:
Net loss	$ (90,346)	$ (203,287)	$ (160,838)	$ (300,319)
Denominator:
Common shares outstanding—basic (shares)	68,248,023	39,375,944	68,227,564	39,375,944
Common shares outstanding—diluted (shares)	68,248,023	39,375,944	68,227,564	39,375,944
Net loss per share attributable to common shareholders of Biohaven Pharmaceutical Holding Company Ltd. - basic (in dollars per share)	$ (1.32)	$ (5.16)	$ (2.36)	$ (7.63)
Net loss per share attributable to common shareholders of Biohaven Pharmaceutical Holding Company Ltd. - diluted (in dollars per share)	$ (1.32)	$ (5.16)	$ (2.36)	$ (7.63)