Stock-Based Compensation - Schedule of Stock Options Outstanding (Detail) (USD $)
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12 Months Ended |
Dec. 31, 2014
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Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items] |
|
Range of Exercise Prices, Lower Range Limit |
$ 1.31us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit |
Range of Exercise Prices, Upper Range Limit |
$ 68.90us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit |
Options Exercisable, Number Exercisable |
1,308,835us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions |
Range One [Member] |
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Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items] |
|
Range of Exercise Prices, Lower Range Limit |
$ 0.01us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = mela_RangeOneMember |
Range of Exercise Prices, Upper Range Limit |
$ 3.00us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = mela_RangeOneMember |
Options Outstanding, Number Outstanding |
1,125,000us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = mela_RangeOneMember |
Options Outstanding, Weighted-Average Remaining Contractual Life (in years) |
9 years 11 months 12 days |
Options Outstanding, Weighted-Average Exercise Price (in dollars per share) |
$ 1.40us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1 / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = mela_RangeOneMember |
Options Exercisable, Number Exercisable |
0us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = mela_RangeOneMember |
Options Exercisable, Weighted-Average Exercise Price (in dollars per share) |
$ 0us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1 / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = mela_RangeOneMember |
Range Two [Member] |
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Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items] |
|
Range of Exercise Prices, Lower Range Limit |
$ 3.01us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = mela_RangeTwoMember |
Range of Exercise Prices, Upper Range Limit |
$ 10.00us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = mela_RangeTwoMember |
Options Outstanding, Number Outstanding |
147,553us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = mela_RangeTwoMember |
Options Outstanding, Weighted-Average Remaining Contractual Life (in years) |
8 years 11 months 23 days |
Options Outstanding, Weighted-Average Exercise Price (in dollars per share) |
$ 6.95us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1 / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = mela_RangeTwoMember |
Options Exercisable, Number Exercisable |
70,443us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = mela_RangeTwoMember |
Options Exercisable, Weighted-Average Exercise Price (in dollars per share) |
$ 7.51us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1 / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = mela_RangeTwoMember |
Range Three [Member] |
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Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items] |
|
Range of Exercise Prices, Lower Range Limit |
$ 10.01us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = mela_RangeThreeMember |
Range of Exercise Prices, Upper Range Limit |
$ 70.00us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = mela_RangeThreeMember |
Options Outstanding, Number Outstanding |
36,282us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = mela_RangeThreeMember |
Options Outstanding, Weighted-Average Remaining Contractual Life (in years) |
7 years 4 months 28 days |
Options Outstanding, Weighted-Average Exercise Price (in dollars per share) |
$ 27.89us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1 / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = mela_RangeThreeMember |
Options Exercisable, Number Exercisable |
30,933us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = mela_RangeThreeMember |
Options Exercisable, Weighted-Average Exercise Price (in dollars per share) |
$ 26.97us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1 / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = mela_RangeThreeMember |
Net Range [Member] |
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Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items] |
|
Range of Exercise Prices, Lower Range Limit |
$ 0.01us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = mela_NetRangeMember |
Range of Exercise Prices, Upper Range Limit |
$ 70.00us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = mela_NetRangeMember |
Options Outstanding, Number Outstanding |
1,308,835us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = mela_NetRangeMember |
Options Outstanding, Weighted-Average Remaining Contractual Life (in years) |
9 years 9 months 7 days |
Options Outstanding, Weighted-Average Exercise Price (in dollars per share) |
$ 2.76us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1 / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = mela_NetRangeMember |
Options Exercisable, Number Exercisable |
101,376us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = mela_NetRangeMember |
Options Exercisable, Weighted-Average Exercise Price (in dollars per share) |
$ 13.45us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1 / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = mela_NetRangeMember |