COMMITMENTS AND CONTINGENCIES - Additional Information (Details) - USD ($)									1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 15, 2016	May 24, 2016	Apr. 22, 2016	Dec. 30, 2015	Dec. 17, 2015	Sep. 19, 2014	Sep. 08, 2014	Jul. 31, 2014	Jul. 31, 2016	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2014
Commitment And Contingency [Line Items]
Accrued expenses										$ 5,212,000	$ 0	$ 5,212,000	$ 0
Donoghue v. Retrophin, Inc. | IRS | Levy Sought on Unpaid Income Taxes by Plaintiff
Commitment And Contingency [Line Items]
Damages sought									$ 4,000,000	$ 2,400,000
Donoghue v. Retrophin, Inc. | Martin Shkreli
Commitment And Contingency [Line Items]
Litigation settlement						$ 2,025,000
Amount paid to plaintiff's counsel		$ 8,249
Accrued expenses												5,200,000
Cash payments of litigation settlement												3,200,000
Donoghue v. Retrophin, Inc. | Martin Shkreli | Legal Fees
Commitment And Contingency [Line Items]
Damages sought			$ 2,800,000		$ 5,000,000
Donoghue v. Retrophin, Inc. | Martin Shkreli | Advancement of Legal Fees [Member]
Commitment And Contingency [Line Items]
Damages sought			$ 400,000		2,800,000
Donoghue v. Retrophin, Inc. | Martin Shkreli | Additional Future Legal Fees
Commitment And Contingency [Line Items]
Damages sought					$ 2,000,000							$ 2,000,000
Donoghue v. Retrophin, Inc. | Martin Shkreli | Plaintiffs
Commitment And Contingency [Line Items]
Litigation settlement						$ 600,000
Lease Agreement | California
Commitment And Contingency [Line Items]
Rent expense	$ 1,100,000						$ 500,000
Leasing contract (in months)	91 months
Tenant allowance from landlord	$ 1,500,000
Loss on leased assets														$ 200,000
Lease Agreement | Massachusetts
Commitment And Contingency [Line Items]
Rent expense								$ 800,000
Lease Agreement | New York
Commitment And Contingency [Line Items]
Rent expense				$ 500,000