Significant Accounting Policies - Concentration of Credit Risk and Other Risks and Uncertainties (Details) - USD ($)	Dec. 31, 2025	Dec. 31, 2024
Accounting Policies [Abstract]
Off-balance sheet concentrations of credit risk	$ 0	$ 0

Concentration Risk, Credit Risk, Financial Instruments, Off-Balance Sheet Risk, Amount

No definition available.

Name:	dnli_ConcentrationRiskCreditRiskFinancialInstrumentsOffBalanceSheetRiskAmount
Namespace Prefix:	dnli_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant