Consolidated Statements of Cash Flows (Parenthetical) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022
Statement of Cash Flows [Abstract]
Short term investments	$ 53.9
Other assets		$ 0.8

Noncash or Part Noncash Acquisition, Value of Short-Term Investments Acquired

No definition available.

Name:	ngne_NoncashOrPartNoncashAcquisitionValueOfShortTermInvestmentsAcquired
Namespace Prefix:	ngne_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration