Analysis of Deferred Tax Assets (Liabilities) (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Net operating loss carryforwards	$ 115,699	$ 94,170
Difference in depreciation and amortization	2,800	2,492
Research and development tax credits	29,127	23,599
Stock-based compensation	13,637	9,036
Deferred rent	2,864	2,849
Deferred revenue	1,213srpt_DeferredTaxAssetsDeferredRevenue	1,219srpt_DeferredTaxAssetsDeferredRevenue
Other	413us-gaap_DeferredTaxAssetsOther	208us-gaap_DeferredTaxAssetsOther
Gross deferred tax assets	165,753us-gaap_DeferredTaxAssetsGross	133,573us-gaap_DeferredTaxAssetsGross
Valuation allowance	(165,753)	(133,573)
Net deferred tax asset	$ 0us-gaap_DeferredTaxAssetsNet	$ 0us-gaap_DeferredTaxAssetsNet

Deferred tax assets deferred revenue.

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Deferred tax assets, depreciation and amortization.

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Deferred tax assets, rental expenses, current.

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Deferred tax assets, research and development.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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Amount after allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible operating loss carryforwards.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences not separately disclosed.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from compensation and benefits costs.

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Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

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