Inventories (Details) - TOI Parent Inc. - USD ($)	Sep. 30, 2021	Dec. 31, 2020	Dec. 31, 2019
Inventory [Line Items]
Total	$ 5,756,578	$ 4,354,232	$ 3,888,988
Oral drug inventory
Inventory [Line Items]
Total	1,712,606	1,414,250	1,140,467
IV drug inventory
Inventory [Line Items]
Total	$ 4,043,972	$ 2,939,982	$ 2,748,521

Amount after valuation and LIFO reserves of inventory expected to be sold, or consumed within one year or operating cycle, if longer.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121566466&loc=d3e6676-107765

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.6(a))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant