Stockholder's Equity - Additional Information (Detail) (USD $)
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1 Months Ended |
3 Months Ended |
14 Months Ended |
1 Months Ended |
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Nov. 30, 2014
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Apr. 30, 2011
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Mar. 31, 2015
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Mar. 31, 2015
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Feb. 28, 2014
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Dec. 31, 2014
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Class of Warrant or Right [Line Items] |
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Common stock, shares issued |
30,941,102us-gaap_StockIssuedDuringPeriodSharesNewIssues |
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20,720,986us-gaap_StockIssuedDuringPeriodSharesNewIssues |
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Additional shares of common available for outstanding exercisable prefunded warrants |
13,081,428mstx_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRightsIssuedToUnderwriter |
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Warrants issued to purchase shares of common stock. |
22,011,265us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights |
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Securities offered and sold combination |
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These securities were offered and sold to the underwriters and the public in units with each Series A unit consisting of one share of our common stock and one-half (0.5) of a warrant and each Series B unit consisting of one pre-funded warrant and one-half (0.5) of a warrant. |
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Gross proceeds of financing |
$ 21,000,000us-gaap_ProceedsFromIssuanceOrSaleOfEquity |
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$ 15,400,000us-gaap_ProceedsFromIssuanceOrSaleOfEquity |
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Proceeds from exercise of warrants |
16,500,000us-gaap_ProceedsFromWarrantExercises |
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Net proceeds from financing |
19,700,000mstx_ProceedsFromIssuanceOfCommonStockAndWarrantsNet |
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14,600,000mstx_ProceedsFromIssuanceOfCommonStockAndWarrantsNet |
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Exercise price of warrants per share |
$ 0.75us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1 |
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Warrants exercisable period |
Nov. 12, 2019 |
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Weighted average sale price |
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$ 0.74mstx_WeightedAverageSalesPrice |
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Common stock, shares issued |
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159,476,176us-gaap_CommonStockSharesIssued |
159,476,176us-gaap_CommonStockSharesIssued |
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159,458,376us-gaap_CommonStockSharesIssued |
Purchase price per share pursuant to the exercise of a repurchase right under the merger agreement |
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$ 0.001us-gaap_TreasuryStockAcquiredAverageCostPerShare |
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First Milestone - FDA Acceptance [Member] |
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Class of Warrant or Right [Line Items] |
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Common stock shares to be issued upon achieving milestones |
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3,839,400us-gaap_CommonStockCapitalSharesReservedForFutureIssuance / us-gaap_EquityInterestIssuedOrIssuableByTypeAxis = mstx_FirstMilestoneSharesMember |
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Second Milestone - FDA Approval [Member] |
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Class of Warrant or Right [Line Items] |
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Common stock shares to be issued upon achieving milestones |
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8,638,650us-gaap_CommonStockCapitalSharesReservedForFutureIssuance / us-gaap_EquityInterestIssuedOrIssuableByTypeAxis = mstx_SecondMilestoneSharesMember |
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Synthrx [Member] |
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Class of Warrant or Right [Line Items] |
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Common stock, shares issued |
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3,050,851us-gaap_CommonStockSharesIssued / us-gaap_BusinessAcquisitionAxis = mstx_SynthrxMember |
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Repurchase of common stock |
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1,454,079us-gaap_TreasuryStockSharesAcquired / us-gaap_BusinessAcquisitionAxis = mstx_SynthrxMember |
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Common stock shares to be issued upon achieving milestones |
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12,478,050us-gaap_CommonStockCapitalSharesReservedForFutureIssuance / us-gaap_BusinessAcquisitionAxis = mstx_SynthrxMember |
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Maximum [Member] |
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Class of Warrant or Right [Line Items] |
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Amount available to sell under equity program |
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30,000,000mstx_AmountAvailableToSellUnderEquityProgram / us-gaap_RangeAxis = us-gaap_MaximumMember |
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Pre-funded Warrants [Member] |
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Class of Warrant or Right [Line Items] |
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Proceeds from exercise of warrants |
$ 100,000us-gaap_ProceedsFromWarrantExercises / us-gaap_StatementEquityComponentsAxis = mstx_PreFundedWarrantsMember |
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Exercise price of warrants per share |
$ 0.01us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1 / us-gaap_StatementEquityComponentsAxis = mstx_PreFundedWarrantsMember |
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Series A [Member] |
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Class of Warrant or Right [Line Items] |
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Common stock, shares issued |
30,941,102us-gaap_StockIssuedDuringPeriodSharesNewIssues / us-gaap_AuctionMarketPreferredSecuritiesStockSeriesAxis = us-gaap_SeriesAMember |
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Number of common stock called by each warrant |
0.5us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByEachWarrantOrRight / us-gaap_AuctionMarketPreferredSecuritiesStockSeriesAxis = us-gaap_SeriesAMember |
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Series A [Member] | Common Stock [Member] |
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Class of Warrant or Right [Line Items] |
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Number of securities in each unit issued |
1mstx_NumberOfSecuritiesInEachUnit / us-gaap_AuctionMarketPreferredSecuritiesStockSeriesAxis = us-gaap_SeriesAMember / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember |
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Series B [Member] |
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Class of Warrant or Right [Line Items] |
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Additional shares of common available for outstanding exercisable prefunded warrants |
13,081,428mstx_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRightsIssuedToUnderwriter / us-gaap_AuctionMarketPreferredSecuritiesStockSeriesAxis = us-gaap_SeriesBMember |
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Number of common stock called by each warrant |
0.5us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByEachWarrantOrRight / us-gaap_AuctionMarketPreferredSecuritiesStockSeriesAxis = us-gaap_SeriesBMember |
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Series B [Member] | Pre-funded Warrants [Member] |
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Class of Warrant or Right [Line Items] |
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Number of securities in each unit issued |
1mstx_NumberOfSecuritiesInEachUnit / us-gaap_AuctionMarketPreferredSecuritiesStockSeriesAxis = us-gaap_SeriesBMember / us-gaap_StatementEquityComponentsAxis = mstx_PreFundedWarrantsMember |
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