Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Taxes [Line Items]
Operating loss carryforwards, beginning of expiration year									2016
Operating loss carryforwards, ending of expiration year									2035
Operating loss carryforwards from exercises of stock options	$ 23,800								$ 23,800
Deferred tax assets, gross	219,824				$ 165,753				219,824	$ 165,753
Net change in valuation allowance for deferred tax assets									54,100	32,200
Increase in warrant valuation						$ (4,256)	$ 3,784	$ 3,251	0	2,779	$ 22,027
Research and development cost	41,376	$ 36,673	$ 29,180	$ 39,165	$ 30,832	$ 21,852	$ 20,641	$ 20,906	146,394	94,231	$ 72,909
Sarepta International C.V. [Member]
Income Taxes [Line Items]
Research and development cost									87,400	$ 48,500
Federal [Member]
Income Taxes [Line Items]
Net operating loss carryforwards	388,200								388,200
State [Member]
Income Taxes [Line Items]
Net operating loss carryforwards	313,100								$ 313,100
Research and Development Credits [Member]
Income Taxes [Line Items]
Research and development credits carryforward, Description									These federal and state research and development credits begin to expire between 2018 and 2035 and between 2016 and 2030, respectively
Research and Development Credits [Member] | Federal [Member]
Income Taxes [Line Items]
Research and development credits carryforward, Amount	26,100								$ 26,100
Research and Development Credits [Member] | Federal [Member] | Minimum [Member]
Income Taxes [Line Items]
Research and development credits carryforward, Expiration period									2018
Research and Development Credits [Member] | Federal [Member] | Maximum [Member]
Income Taxes [Line Items]
Research and development credits carryforward, Expiration period									2035
Research and Development Credits [Member] | State [Member]
Income Taxes [Line Items]
Research and development credits carryforward, Amount	$ 7,200								$ 7,200
Research and Development Credits [Member] | State [Member] | Minimum [Member]
Income Taxes [Line Items]
Research and development credits carryforward, Expiration period									2016
Research and Development Credits [Member] | State [Member] | Maximum [Member]
Income Taxes [Line Items]
Research and development credits carryforward, Expiration period									2030