Amount of amortization expense attributable to debt issuance costs.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount of the required periodic payments applied to principal.

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Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

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Amount of cash inflow from contractual arrangement with the lender, including but not limited to, letter of credit, standby letter of credit and revolving credit arrangements.

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Amount of cash outflow for payment of an obligation from a lender, including but not limited to, letter of credit, standby letter of credit and revolving credit arrangements.

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Debt - Additional Information (Details) - USD ($)			9 Months Ended		12 Months Ended
Debt - Additional Information (Details) - USD ($)	Jun. 30, 2020	Feb. 26, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Jun. 18, 2021
Debt
Unamortized debt issuance costs			$ 229,725
TOI Parent Inc.
Debt
Repayments in quarterly installments			187,500	$ 93,750
Amount borrowed					$ 7,500,000
Aggregate principal amount		$ 10,000,000
Available borrowing capacity			0		2,500,000
Unamortized debt issuance costs			229,725		282,512	$ 0
Amortization of the debt issuance costs			52,787	41,950	59,988	$ 0
TOI Parent Inc. \| Variable Rate Revolving Credit Facility Term Loan, interest at LIBOR plus applicable margin, due February 26, 2025
Debt
Repayments in quarterly installments	$ 93,750	187,500
Amount borrowed			5,125,000
Amount drawn			2,500,000
Aggregate principal amount		$ 10,000,000					$ 9,000,000
Outstanding principal balance paid			2,000,000
Unamortized debt issuance costs			229,725		$ 282,512
Amortization of the debt issuance costs			$ 52,787	$ 41,950