CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement of Comprehensive Income [Abstract]
Net loss	$ (196,628)	$ (106,167)	$ (550,499)	$ (379,541)
Other comprehensive income, net of tax:
Foreign currency translation adjustments	324	0	324	0
Net unrealized losses related to available-for-sale debt securities	(73)	0	(73)	0
Other comprehensive income	251	0	251	0
Comprehensive loss	(196,377)	(106,167)	(550,248)	(379,541)
Less: comprehensive loss attributable to non-controlling interests	(1,439)	0	(1,439)	0
Comprehensive loss attributable to Biohaven Pharmaceutical Holding Company Ltd.	$ (194,938)	$ (106,167)	$ (548,809)	$ (379,541)