Commitments and Contingencies - Additional Information (Detail) (USD $)	1 Months Ended		12 Months Ended			1 Months Ended
	Apr. 30, 2013	Feb. 28, 2013 CreditFacility	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jun. 30, 2014 sqft	Jan. 31, 2014 sqft
Commitments and Contingencies [Line Items]
Letters of credit amount issued		$ 7,300,000
Maximum royalty to Charley's Fund			3,400,000
Upfront and development significant milestone payments			0	0	0
Obligated to make milestone payments			26,800,000
Receivables under satisfaction of milestones			21,100,000
Upfront payments recognized under agreement	7,100,000		0	1,000,000
Law affected under lawsuit filling			The consolidated amended complaint alleges that Sarepta and certain of its officers violated the federal securities laws in connection with disclosures related to eteplirsen
Number of days to amend plaintiffs complaint			28 days
Certificate of deposit purchased		7,300,000
Number of letter of credit		2
Assignors [Member]
Commitments and Contingencies [Line Items]
Upfront payments recognized under agreement			300,000
Development and commercial milestone payments			2,700,000
Lease Agreements [Member]
Commitments and Contingencies [Line Items]
Letters of credit amount issued			$ 600,000
Total rental space			77,390
Lease expiration date			2021-01
Corvallis, Oregon [Member]
Commitments and Contingencies [Line Items]
Lease expiration date			2020-12
Sublease [Member]
Commitments and Contingencies [Line Items]
Lease expiration date						2021-02	2015-07
Additional rental space under amendment						10,939	15,077