Organization and Business Description (Details) $ / shares in Units, $ in Thousands	Dec. 18, 2025 USD ($) $ / shares shares	Dec. 16, 2025 USD ($) shares	Mar. 31, 2026 vote state office	Dec. 06, 2025	Apr. 16, 2025
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Number of offices | office			27
Number of states | state			15
2025 Equity Incentive Plan | Restricted Stock Units (RSUs)
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Share issued (in shares) | shares		5,440,720
TRA Parties
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Interest rate		85.00%
Management Holdco | Member Notes
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Debt instrument, term		7 years
Management Holdco | Member Notes | If Balance Is At Least $550,000
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Principal balance, threshold		$ 550
Management Holdco | Member Notes | If Balance Is At Least $550,000 | Minimum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Debt instrument, term		3 years
Management Holdco | Member Notes | If Balance Is At Least $550,000 | Maximum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Debt instrument, term		7 years
Management Holdco | Member Notes | If Balance Is Less Than $550,000
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Principal balance, threshold		$ 550
Management Holdco | Member Notes | If Balance Is Less Than $550,000 | Minimum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Debt instrument, term		2 years
Management Holdco | Member Notes | If Balance Is Less Than $550,000 | Maximum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Debt instrument, term		7 years
AT Umbrella LLC
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Membership interest units acquired (in shares) | shares	12,650,000
AT Umbrella LLC | Capital Account Notes
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Aggregate principal amount		$ 187,800
AT Umbrella LLC | Capital Account Notes | Notes Payable
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Aggregate principal amount		$ 187,800
AT Umbrella LLC | Capital Account Notes | Minimum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Debt instrument, term		2 years
Interest rate		6.31%
AT Umbrella LLC | Capital Account Notes | Minimum | Notes Payable
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Interest rate				6.31%
AT Umbrella LLC | Capital Account Notes | Maximum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Debt instrument, term		7 years
Interest rate		7.50%
AT Umbrella LLC | Capital Account Notes | Maximum | Notes Payable
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Interest rate				7.50%
AT Umbrella LLC | Holdover Note
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Debt instrument, term		8 years
Aggregate principal amount		$ 162,300
Interest rate		7.63%
AT Umbrella LLC | Holdover Note | Notes Payable
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Debt instrument, term		8 years
Aggregate principal amount		$ 162,300
Interest rate				7.63%
Post-service obligation payment period		7 years
Class A Common Stock
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Number of votes | vote			1
Class A Common Stock | IPO
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Proceeds to purchase shares (in shares) | shares	12,650,000
Sale of stock, price per share (in dollars per share) | $ / shares	$ 16.00
Proceeds from issuance initial public offering	$ 188,200
Underwriting discounts and commissions	14,200
Offering costs	$ 9,900
Class A Common Stock | Over-Allotment Option
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Proceeds to purchase shares (in shares) | shares	1,650,000
Class B Common Stock
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Number of votes | vote			10
AT Umbrella LLC
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Equity method investment, ownership percentage					11.40%
Andersen Tax Holdings LLC | Andersen Aggregator LLC
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Equity method investment, ownership percentage	100.00%
Andersen Aggregator LLC | Class B Common Stock | Andersen Group Inc
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Proceeds to purchase shares (in shares) | shares	98,302,500