CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Statement [Abstract]
Product revenue, net	$ 17,664	$ 0	$ 28,513	$ 0
Cost of goods sold	4,244	0	7,726	0
Gross profit	13,420	0	20,787	0
Operating expenses:
Research and development	57,044	61,674	155,539	278,654
Selling, general and administrative	119,533	28,778	339,936	65,467
Total operating expenses	176,577	90,452	495,475	344,121
Loss from operations	(163,157)	(90,452)	(474,688)	(344,121)
Other income (expense):
Interest expense	(4,608)	0	(4,835)	0
Non-cash interest expense on mandatorily redeemable preferred shares	(7,310)	(4,378)	(19,864)	(8,333)
Non-cash interest expense on liability related to sale of future royalties	(11,955)	(7,312)	(31,950)	(19,284)
Change in fair value of derivatives	(1,940)	(1,717)	(7,071)	(2,980)
Loss from equity method investment	(607)	(1,993)	(3,472)	(4,308)
Other	(3,062)	8	(3,278)	(25)
Total other expense, net	(29,482)	(15,392)	(70,470)	(34,930)
Loss before provision for income taxes	(192,639)	(105,844)	(545,158)	(379,051)
Provision for income taxes	3,989	323	5,341	490
Net loss	(196,628)	(106,167)	(550,499)	(379,541)
Less: Net loss attributable to non-controlling interests	(1,439)	0	(1,439)	0
Net loss attributable to Biohaven Pharmaceutical Holding Company Ltd.	$ (195,189)	$ (106,167)	$ (549,060)	$ (379,541)
Net loss per share attributable to Biohaven Pharmaceutical Holding Company Ltd - basic and diluted (in dollars per share)	$ (3.27)	$ (2.04)	$ (9.42)	$ (8.04)
Weighted average common shares outstanding - basic and diluted (shares)	59,677,989	52,077,240	58,282,697	47,210,615