Related Party Transactions	9 Months Ended
Dec. 31, 2017
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions In July 2016, the Company entered into a formal services agreement with RSI, effective April 29, 2016, under which RSI agreed to provide certain administrative and R&D services to the Company. Under this services agreement, the Company pays or reimburses RSI for expenses it, or third parties acting on its behalf, incurs for the Company. For any general and administrative, or G&A, and R&D activities performed by RSI employees, RSI charges the Company the employee compensation expense plus a pre-determined mark-up. Employee compensation expense, inclusive of base salary and fringe benefits, is determined based upon the relative percentage of time utilized on Company matters by the respective employee. All other third-party costs are billed to the Company at cost. The accompanying interim unaudited condensed consolidated financial statements include third-party expenses incurred on behalf of the Company that have been incurred by RSI and RSL. In February 2017, the Company and MSI amended and restated the services agreement, effective as of November 11, 2016, to include MSG as a services recipient. In addition, in February 2017, MSG entered into a separate services agreement with RSG, effective as of November 11, 2016, for the provisioning of services by RSG to MSG in relation to services related to clinical development, administrative and finance and accounting activities. The Company refers to the amended and restated services agreement with RSI and the services agreement with RSG, collectively, as the Services Agreements. Under the Services Agreements, for the three months ended December 31, 2017 and 2016, the Company incurred expenses of $2.9 million and $2.7 million, respectively, inclusive of the pre-determined mark-up. For the nine months ended December 31, 2017 and 2016, the Company incurred expenses of $5.0 million and $6.8 million, respectively, inclusive of the pre-determined mark-up. These amounts are included in R&D and G&A based upon the service performed under the Services Agreements.

Related Party Transactions

In July 2016, the Company entered into a formal services agreement with RSI, effective April 29, 2016, under which RSI agreed to provide certain administrative and R&D services to the Company. Under this services agreement, the Company pays or reimburses RSI for expenses it, or third parties acting on its behalf, incurs for the Company. For any general and administrative, or G&A, and R&D activities performed by RSI employees, RSI charges the Company the employee compensation expense plus a pre-determined mark-up. Employee compensation expense, inclusive of base salary and fringe benefits, is determined based upon the relative percentage of time utilized on Company matters by the respective employee. All other third-party costs are billed to the Company at cost. The accompanying interim unaudited condensed consolidated financial statements include third-party expenses incurred on behalf of the Company that have been incurred by RSI and RSL.

In February 2017, the Company and MSI amended and restated the services agreement, effective as of November 11, 2016, to include MSG as a services recipient. In addition, in February 2017, MSG entered into a separate services agreement with RSG, effective as of November 11, 2016, for the provisioning of services by RSG to MSG in relation to services related to clinical development, administrative and finance and accounting activities. The Company refers to the amended and restated services agreement with RSI and the services agreement with RSG, collectively, as the Services Agreements.

Under the Services Agreements, for the three months ended December 31, 2017 and 2016, the Company incurred expenses of $2.9 million and $2.7 million, respectively, inclusive of the pre-determined mark-up. For the nine months ended December 31, 2017 and 2016, the Company incurred expenses of $5.0 million and $6.8 million, respectively, inclusive of the pre-determined mark-up. These amounts are included in R&D and G&A based upon the service performed under the Services Agreements.