Commitments and Contingencies - Additional Information (Detail)	1 Months Ended						12 Months Ended
	Sep. 30, 2015 USD ($)	Aug. 31, 2015 ft²	Feb. 28, 2015 ft²	Jun. 30, 2014 ft²	Jan. 31, 2014 ft²	Apr. 30, 2013 USD ($)	Dec. 31, 2015 USD ($) ft²	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Commitments and Contingencies [Line Items]
Letters of credit amount issued	$ 10,700,000
Upfront and development significant milestone payments							$ 200,000	$ 0	$ 0
Upfront milestone payment							$ 0
Development and commercial milestone payments	39,200,000
Law affected under lawsuit filling							The consolidated amended complaint alleged 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	$ 10,700,000
Certificate of deposit maturity date							2016-09
Restricted investments							$ 10,700,000
University of Western Australia [Member]
Commitments and Contingencies [Line Items]
Upfront payments recognized under agreement						$ 7,100,000	200,000	$ 0	$ 1,000,000
Upfront milestone payment							30,000,000
Aggregate up-front payment							$ 20,000,000
Corvallis, Oregon [Member]
Commitments and Contingencies [Line Items]
Lease expiration date							2020-12
Sublease [Member]
Commitments and Contingencies [Line Items]
Lease expiration date		2017-09	2016-02	2021-02	2015-07
Additional rental space under amendment | ft²		15,077	7,461	10,939	15,077
Lease Agreements [Member]
Commitments and Contingencies [Line Items]
Total rental space | ft²							77,390
Lease expiration date							2021-01
Letters of credit amount issued							$ 600,000