Subsequent Events - Additional Information - (Details) - USD ($) $ in Millions					3 Months Ended
	May 02, 2023	Apr. 21, 2023	Apr. 20, 2023	Apr. 07, 2023	Mar. 31, 2023
MGTA-45 [Member]
Subsequent Event [Line Items]
Other Income					$ 1.1
Subsequent Event [Member] | MGTA-45 [Member]
Subsequent Event [Line Items]
Cash Consideration				$ 0.8
Milestone Payment				10.0
Subsequent Event [Member] | MGTA-145 [Member]
Subsequent Event [Line Items]
Cash Consideration			$ 1.0
Milestone Payment			$ 5.0
Subsequent Event [Member] | MGTA-117 [Member]
Subsequent Event [Line Items]
Cash Consideration		$ 1.5
Milestone Payment		$ 5.0
Subsequent Event [Member] | Dianthus [Member]
Subsequent Event [Line Items]
Business Combination, Contingent Consideration Arrangements, Description	At or prior to the effective time of the Merger, the Company will enter into a Contingent Value Rights Agreement (the “CVR Agreement”) with a rights agent (“Rights Agent”) pursuant to which the Company’s pre-Merger common stockholders will receive one contingent value right (each, a “CVR”) for each outstanding share of common stock held by such stockholder on such date. Each CVR will represent the contractual right to receive certain net proceeds, if any, derived from any consideration that is paid to the Company as a result of the disposition of the Company’s pre-Merger legacy assets by December 31, 2023, net of any indemnity obligations, transaction costs and certain other expenses, during the period that is three years after the closing of the Merger. The contingent payments under the CVR Agreement, if they become payable, will become payable to the Rights Agent for subsequent distribution to the holders of the CVRs subject to certain withholdings for expenses and potential indemnity claims. In the event that no such proceeds are received, holders of the CVRs will not receive any payment pursuant to the CVR Agreement.
Merger Agreement Potential Termination Fee Payable	$ 13.3
Merger Agreement Potential Termination Fee Receivable	13.3
Subsequent Event [Member] | Maximum [Member] | MGTA-45 [Member]
Subsequent Event [Line Items]
Reimbursement Payment				$ 0.5
Subsequent Event [Member] | Maximum [Member] | Dianthus [Member]
Subsequent Event [Line Items]
Merger Agreement Potential Costs And Expenses Payable Upon Termination	1.5
Merger Agreement Potential Costs And Expenses Receivable Upon Termination	$ 1.5