Organization and Nature of Operations (Details) $ / shares in Units, $ in Millions		12 Months Ended
	Sep. 15, 2025 USD ($) $ / shares shares	Dec. 31, 2025 vote store state shares
Product Information [Line Items]
Number of Stores | store		181
Number of states | state		7
Recapitalized ownership (in units)		43,079,227
Black Rock OpCo | Affiliate Of Co-Founders | LLC Units
Product Information [Line Items]
Sale of stock (in shares)	3,118,938
Public offering price | $ / shares	$ 20.00
Net proceeds from IPO | $	$ 62.4
Black Rock OpCo | LLC Units held by Black Rock Coffee Bar, Inc. | LLC Units
Product Information [Line Items]
Sale of stock (in shares)	3,857,642
Net proceeds from IPO | $	$ 71.8
Continuing Equity Owners | LLC Units
Product Information [Line Items]
Sale of stock (in shares)	13,054,122
Net proceeds from IPO | $	$ 242.8
Class A Common stock
Product Information [Line Items]
Number of votes per share | vote		1
Class B Common stock
Product Information [Line Items]
Number of votes per share | vote		1
Class C Common stock
Product Information [Line Items]
Number of votes per share | vote		10
Share ownership threshold		33.00%
IPO
Product Information [Line Items]
Sale of stock (in shares)	16,911,764
Public offering price | $ / shares	$ 20.00
Net proceeds from IPO | $	$ 306.5
Over-Allotment Option
Product Information [Line Items]
Sale of stock (in shares)	2,205,882