Income Taxes - Summary of Deferred Tax Assets and Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Deferred tax assets:
Net operating loss carryforward	$ 57,367	$ 35,086
Capitalized research and developmental costs	12,925	27,794
Inventory	689us-gaap_DeferredTaxAssetsInventory	0us-gaap_DeferredTaxAssetsInventory
Reserves & accrued expenses	135	0
Warrant Liability	(3,123)mela_DeferredTaxAssetsWarrantLiablity	0mela_DeferredTaxAssetsWarrantLiablity
Property & equipment	(785)	0
Non-cash compensation	3,840	3,681
Total deferred tax assets	71,048us-gaap_DeferredTaxAssetsGross	66,561us-gaap_DeferredTaxAssetsGross
Less valuation allowance	(71,048)	(66,561)
Net deferred tax assets	$ 0us-gaap_DeferredTaxAssetsNet	$ 0us-gaap_DeferredTaxAssetsNet

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Amount before 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 temporary differences from in-process research and development costs expensed in connection with a business combination.

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

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Amount of deferred tax liability attributable to taxable temporary differences from property, plant, and equipment.

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