Property and Equipment, Net - Additional Information (Details) - USD ($)	3 Months Ended	9 Months Ended	12 Months Ended
Dec. 31, 2018	Sep. 30, 2021	Sep. 30, 2020	Sep. 19, 2018	Dec. 31, 2020	Dec. 31, 2019
TOI Parent Inc.
Property and Equipment, Net
Depreciation expense	$ 56,508	$ 562,676	$ 513,830	$ 338,196	$ 690,499	$ 418,461

The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585

Name:	us-gaap_Depreciation
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration