Notes Payable - Notes Payable to Related Parties (Details)		1 Months Ended	3 Months Ended	12 Months Ended
	Dec. 31, 2016 USD ($)	May 31, 2017 USD ($)	Mar. 31, 2017 installment	Dec. 31, 2016 USD ($)
Majority Shareholder | Biohaven Pharmaceuticals, Inc.
Notes Payable to Related Parties
Ownership interest acquired	100.00%			100.00%
Aggregate purchase consideration	$ 595,000.000			$ 595,000
Number of installments in which notes are payable | installment			5
Number of interest only related party notes payable installments | installment			4
Interest rate of notes			4.50%
Initial public offering | Subsequent Event
Notes Payable to Related Parties
Repayment of principal amount to related party		$ 595,000.000
Repayment of interest amount to related party		$ 9,000