Condensed Statements of Operations and Comprehensive Loss (Unaudited) (Parenthetical) $ in Thousands	3 Months Ended
Mar. 31, 2020 USD ($)
Income Statement [Abstract]
Research and development, related party	$ 132
General and administrative, related party	$ 111

Related party transaction general and administrative expenses.

No definition available.

Name:	kura_RelatedPartyTransactionGeneralAndAdministrativeExpenses
Namespace Prefix:	kura_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration