Acquisition of Biohaven Pharmaceuticals, Inc (Details) $ in Thousands		3 Months Ended	9 Months Ended		12 Months Ended
	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 installment	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($) item
Acquisition of Biohaven Pharmaceuticals, Inc.
Net loss attributable to non-controlling interests		$ 50		$ 69
Biohaven Pharmaceuticals, Inc. | Majority Shareholder
Acquisition of Biohaven Pharmaceuticals, Inc.
Ownership interest acquired	100.00%				100.00%
Aggregate purchase consideration	$ 595
Number of founders | item					3
Equity share percentage owned by each founders	33.33%				33.33%
Number of installments in which notes were payable | installment			5
Number of interest only related party notes payable installments | installment			4
Interest rate of notes			4.50%
Carrying value of non-controlling interest derecognized	$ 86				$ 86
Reduction to additional paid-in capital					$ 509
Net loss attributable to non-controlling interests		$ 50		$ 69