Convertible Preferred Stock- Summary of Preferred Stock (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2025	Jun. 30, 2025	Mar. 31, 2025	Sep. 30, 2025
Increase (Decrease) in Temporary Equity [Roll Forward]
Temporary equity, beginning balance (in shares)			175,190,188	175,190,188
Temporary equity, beginning balance	$ 126,700	$ 94,147	$ 74,475	$ 74,475
Exercise of preferred stock warrants ( in shares)				1,988,999
Exercise of preferred stock warrant	264	650	130	$ 455
Issuance of Series E (in shares)				58,774,312
Issuance of Series E		31,903	19,542	$ 40,130
Conversion of redeemable convertible preferred stock to common stock upon IPO (in shares)				(235,953,499)
Conversion of redeemable convertible preferred stock to common stock upon IPO	$ (126,964)			$ (115,060)
Temporary equity, ending balance (in shares)	0			0
Temporary equity, ending balance	$ 0	$ 126,700	$ 94,147	$ 0
Series Seed Convertible Preferred Stock
Increase (Decrease) in Temporary Equity [Roll Forward]
Temporary equity, beginning balance (in shares)			15,851,401	15,851,401
Temporary equity, beginning balance			$ 1,337	$ 1,337
Exercise of preferred stock warrants ( in shares)				988,999
Exercise of preferred stock warrant				$ 83
Conversion of redeemable convertible preferred stock to common stock upon IPO (in shares)				(16,840,400)
Conversion of redeemable convertible preferred stock to common stock upon IPO				$ (1,420)
Temporary equity, ending balance (in shares)	0			0
Temporary equity, ending balance	$ 0			$ 0
Series A Convertible Preferred Stock
Increase (Decrease) in Temporary Equity [Roll Forward]
Temporary equity, beginning balance (in shares)			22,399,370	22,399,370
Temporary equity, beginning balance			$ 5,600	$ 5,600
Conversion of redeemable convertible preferred stock to common stock upon IPO (in shares)				(22,399,370)
Conversion of redeemable convertible preferred stock to common stock upon IPO				$ (5,600)
Temporary equity, ending balance (in shares)	0			0
Temporary equity, ending balance	$ 0			$ 0
Series B Convertible Preferred Stock
Increase (Decrease) in Temporary Equity [Roll Forward]
Temporary equity, beginning balance (in shares)			5,913,964	5,913,964
Temporary equity, beginning balance			$ 2,200	$ 2,200
Exercise of preferred stock warrants ( in shares)				1,000,000
Exercise of preferred stock warrant				$ 372
Conversion of redeemable convertible preferred stock to common stock upon IPO (in shares)				(6,913,964)
Conversion of redeemable convertible preferred stock to common stock upon IPO				$ (2,572)
Temporary equity, ending balance (in shares)	0			0
Temporary equity, ending balance	$ 0			$ 0
Series C Convertible Preferred Stock
Increase (Decrease) in Temporary Equity [Roll Forward]
Temporary equity, beginning balance (in shares)			50,116,284	50,116,284
Temporary equity, beginning balance			$ 21,550	$ 21,550
Conversion of redeemable convertible preferred stock to common stock upon IPO (in shares)				(50,116,284)
Conversion of redeemable convertible preferred stock to common stock upon IPO				$ (21,550)
Temporary equity, ending balance (in shares)	0			0
Temporary equity, ending balance	$ 0			$ 0
Series D Convertible Preferred Stock
Increase (Decrease) in Temporary Equity [Roll Forward]
Temporary equity, beginning balance (in shares)			80,909,169	80,909,169
Temporary equity, beginning balance			$ 43,788	$ 43,788
Conversion of redeemable convertible preferred stock to common stock upon IPO (in shares)				(80,909,169)
Conversion of redeemable convertible preferred stock to common stock upon IPO				$ (43,788)
Temporary equity, ending balance (in shares)	0			0
Temporary equity, ending balance	$ 0			$ 0
Series E Convertible Preferred Stock
Increase (Decrease) in Temporary Equity [Roll Forward]
Temporary equity, beginning balance (in shares)			0	0
Temporary equity, beginning balance			$ 0	$ 0
Issuance of Series E (in shares)				58,774,312
Issuance of Series E				$ 40,130
Conversion of redeemable convertible preferred stock to common stock upon IPO (in shares)				(58,774,312)
Conversion of redeemable convertible preferred stock to common stock upon IPO				$ (40,130)
Temporary equity, ending balance (in shares)	0			0
Temporary equity, ending balance	$ 0			$ 0

SHOULDER INNOVATIONS, INC. 10-Q