Earnings Per Share - Schedule of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Numerator:
Net income	$ 17,738	$ 50,576
Net income attributable to noncontrolling interest	17,244
Net income attributable to Andersen Group Inc. stockholders, basic	494
Net income attributable to Andersen Group Inc. stockholders, diluted	$ 494
Denominator:
Weighted average number of shares of Class A common stock outstanding, basic (in shares)	12,650,000
Effect of dilutive RSUs (in shares)	1,768,886
Effect of dilutive LTIP Units (in shares)	395,835
Weighted average number of shares of Class A common stock outstanding, diluted (in shares)	14,814,721
Earnings per share:
Earnings per share attributable to Class A common stockholders, basic (in dollars per share)	$ 0.04
Earnings per share attributable to Class A common stockholders, diluted (in dollars per share)	$ 0.03