Description of business and summary of significant accounting policies, Initial Public Offering and Reorganization Transactions (Details) $ / shares in Units, $ in Millions			6 Months Ended
		Jan. 16, 2024 USD ($) LLCUnit Vote shares $ / shares	Jun. 30, 2024 Vote LLCUnit
Initial Public Offering [Abstract]
Ownership interests recapitalized into LLC interests | LLCUnit		44,871,794
Smith Douglas Holdings LLC [Member] | Continuing Equity Owners [Member]
Initial Public Offering [Abstract]
LLC Interests Purchased | LLCUnit			2,435,897
Common Class A [Member]
Initial Public Offering [Abstract]
Number of votes per share | Vote			1
LLC Interests Purchased | LLCUnit		6,410,257
Value of LLC Interests Purchased | $		$ 125.2
Common Class A [Member] | Smith Douglas Holdings LLC [Member] | Continuing Equity Owners [Member]
Initial Public Offering [Abstract]
LLC Interests Purchased | shares		2,435,897
Value of LLC Interests Purchased | $		$ 47.6
Common Class B [Member]
Initial Public Offering [Abstract]
Number of votes per share | Vote	[1]		10
Maximum number of Class B common stock outstanding compared to total of Class A and Class B common stock outstanding for occurrence of Sunset		10.00%
Shares issued (in shares) | shares		42,435,897
IPO [Member] | Common Class A [Member]
Initial Public Offering [Abstract]
Number of shares issued (in shares) | shares		8,846,154
Net proceeds | $		$ 172.8
Number of votes per share | Vote		1
Offering price per share (in dollars per share) | $ / shares		$ 21
IPO [Member] | Common Class B [Member]
Initial Public Offering [Abstract]
Number of votes per share | Vote		10
Underwriters' Option [Member] | Common Class A [Member]
Initial Public Offering [Abstract]
Number of shares issued (in shares) | shares		1,153,846

[1] Each share of Class B common stock entitles its holders to ten votes per share on all matters presented to the stockholders and on which the holders of the Class B common stock are entitled to vote; provided, that each share of Class B common stock will only be entitled to one vote per share on all matters presented to the stockholders generally upon the Sunset Date.