Marketable Securities and Fair Value of Financial Assets and Liabilities - Additional Information (Detail) - USD ($)	Sep. 30, 2019	Sep. 30, 2018
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Abstract]
Fair value asset, transfers between Level 1, Level 2 and Level 3, amount	$ 0	$ 0

Amount of transfers of assets measured on a recurring basis between Level 1, Level 2 and Level 3.

No definition available.

Name:	umrx_FairValueAssetsTransfersBetweenLevelOneTwoAndThree
Namespace Prefix:	umrx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant