Direct Digital Holdings Quarterly report pursuant to Section 13 or 15(d)

Basis of Presentation and Summary of Significant Accounting Policies - Revenue Recognition (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Concentrations of credit risk
Contract liabilities	$ 1,146,186		$ 1,146,186		$ 1,348,093
Minimum
Concentrations of credit risk
Payment term			30 days
Maximum
Concentrations of credit risk
Payment term			90 days
Revenue \| Customer concentration risk \| Customer A
Concentrations of credit risk
Concentration risk (as a percent)	69.80%	23.20%	60.20%	16.70%
Revenue \| Customer concentration risk \| Customer I
Concentrations of credit risk
Concentration risk (as a percent)	3.90%	12.20%	7.70%	4.10%
Revenue \| Customer concentration risk \| Customer E
Concentrations of credit risk
Concentration risk (as a percent)	4.00%	11.10%	6.40%	15.40%
Revenue \| Customer concentration risk \| Customer H
Concentrations of credit risk
Concentration risk (as a percent)	3.30%	7.50%	2.50%	4.30%
Revenue \| Customer concentration risk \| Customer F
Concentrations of credit risk
Concentration risk (as a percent)				12.70%