v3.26.1
BUSINESS AND LIQUIDITY - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Millions
May 04, 2026
Mar. 01, 2026
Mar. 31, 2026
Feb. 06, 2026
Jan. 26, 2026
Dec. 31, 2025
Dec. 31, 2024
Apr. 30, 2024
Business Disclosure [Line Items]                
Cash, cash equivalents and marketable securities     $ 46.8     $ 54.7    
Common stock, par value (in dollars per share)     $ 0.0001     $ 0.0001 $ 0.0001 $ 0.0001
Subsequent Event [Member]                
Business Disclosure [Line Items]                
Common stock, par value (in dollars per share)   $ 0.0001   $ 0.0001 $ 0.0001      
Merger And Reorganization Concurrent Financing   $ 505.5            
Merger And Reorganization Cash And Cash Equivalents At Carrying Value   37.5            
Subsequent Event [Member] | Purchase Commitment [Member]                
Business Disclosure [Line Items]                
Concurrent financing   $ 505.5            
Subsequent Event [Member] | Pre-Merger Equityholders of Candid [Member]                
Business Disclosure [Line Items]                
Merger And Reorganization Combined Ownership Percentage   57.55%            
Merger And Reorganization Consideration Transferred Expected Value   $ 750.0            
Subsequent Event [Member] | Pre-Merger Equityholders of Candid [Member] | Concurrent Financing [Member]                
Business Disclosure [Line Items]                
Merger And Reorganization Combined Ownership Percentage   38.80%            
Subsequent Event [Member] | Pre-Merger Equityholders of Rallybio [Member]                
Business Disclosure [Line Items]                
Merger And Reorganization Consideration Transferred Expected Value   $ 47.5            
Subsequent Event [Member] | Pre-Merger Equityholders of Rallybio [Member] | Candid [Member]                
Business Disclosure [Line Items]                
Merger And Reorganization Combined Ownership Percentage   3.65% 3.65%          
Subsequent Event [Member] | Merger Agreement [Member]                
Business Disclosure [Line Items]                
Business Combination, Pro Forma Information, Description   pre-Merger equityholders of Candid (other than investors in the Concurrent Financing) are expected to own approximately 57.55% of the combined company, pre-Merger equityholders of Rallybio are expected to own approximately 3.65% of the combined company and the Investors in the Concurrent Financing are expected to own approximately 38.80% of the combined company (assuming proceeds from the Concurrent Financing of $505.5 million), in each case, calculated on a fully diluted basis, using the treasury stock method, and subject to certain assumptions, including (i) a valuation for Rallybio of $47.5 million (assuming Rallybio has net cash (“Rallybio Net Cash”) of $37.5 million as of the closing of the Merger (the “Closing” and such date, the “Closing Date”)), (ii) a fixed valuation for Candid of $750.0 million, and (iii) the relative capitalization of Rallybio and Candid.            
Subsequent Event [Member] | Rally bio [Member]                
Business Disclosure [Line Items]                
Business combination termination fee received $ 50.0              
Reimbursement of transaction costs $ 0.4