Fair Value Measurements - Schedule of Financial Assets and Liabilities to Fair Value Measurement On Recurring Basis and Level of Input Measurement (Details) - Fair Value, Recurring Basis - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Total financial assets	$ 349,125	$ 273,303
Level 1
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Total financial assets	254,376	205,929
Level 2
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Total financial assets	94,749	67,374
Level 3
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Total financial assets	0	0
Money market funds
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Total financial assets	254,376	202,965
Money market funds \| Level 1
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Total financial assets	254,376	202,965
Money market funds \| Level 2
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Total financial assets	0	0
Money market funds \| Level 3
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Total financial assets	0	0
U.S. treasury bills
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Total financial assets		2,964
U.S. treasury bills \| Level 1
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Total financial assets		2,964
U.S. treasury bills \| Level 2
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Total financial assets		0
U.S. treasury bills \| Level 3
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Total financial assets		0
Corporate debt securities
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Total financial assets	72,277	37,978
Corporate debt securities \| Level 1
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Total financial assets	0	0
Corporate debt securities \| Level 2
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Total financial assets	72,277	37,978
Corporate debt securities \| Level 3
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Total financial assets	0	0
U.S. government bonds
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Total financial assets	17,016	26,904
U.S. government bonds \| Level 1
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Total financial assets	0	0
U.S. government bonds \| Level 2
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Total financial assets	17,016	26,904
U.S. government bonds \| Level 3
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Total financial assets	0	0
Commercial paper
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Total financial assets	5,456
Commercial paper \| Level 1
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Total financial assets	0
Commercial paper \| Level 2
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Total financial assets	5,456
Commercial paper \| Level 3
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Total financial assets	$ 0
Agency bonds
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Total financial assets		2,492
Agency bonds \| Level 1
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Total financial assets		0
Agency bonds \| Level 2
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Total financial assets		2,492
Agency bonds \| Level 3
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Total financial assets		$ 0

Mirum Pharmaceuticals, Inc. 10-K