Name:	us-gaap_AccountsAndOtherReceivablesNetCurrent
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Period Type:	instant

The valuation allowance as of the balance sheet date to reduce the gross amount of receivables to estimated net realizable value, which would be presented in parentheses on the face of the balance sheet.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481962/310-10-50-4

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Carrying value of amounts transferred to third parties for security purposes that are expected to be returned or applied towards payment within one year or during the operating cycle, if shorter.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(8))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1

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Data Type:	xbrli:monetaryItemType
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Carrying amount as of the balance sheet date of interest earned but not received. Also called accrued interest or accrued interest receivable.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 946
-SubTopic 310
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480833/946-310-45-1

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(3)(a)(4))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1

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Data Type:	xbrli:monetaryItemType
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Period Type:	instant

Amount of current assets classified as other.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 852
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 10
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481372/852-10-55-10

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(8))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1

Name:	us-gaap_OtherAssetsCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
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Period Type:	instant

Amount of asset related to consideration paid in advance for costs that provide economic benefits in future periods, and amount of other assets that are expected to be realized or consumed within one year or the normal operating cycle, if longer.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(9))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Amount of asset related to consideration paid in advance for rent that provides economic benefits within a future period of one year or the normal operating cycle, if longer.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Subparagraph (g)(3)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483467/210-10-45-1

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 340
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483032/340-10-45-1

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Topic 340
-SubTopic 10
-Name Accounting Standards Codification
-Section 05
-Paragraph 5
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482955/340-10-05-5

Name:	us-gaap_PrepaidRent
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Carrying amount as of the balance sheet date of value added taxes due either from customers arising from sales on credit terms, or as previously overpaid to tax authorities. For classified balance sheets, represents the current amount receivable, that is amounts expected to be collected within one year or the normal operating cycle, if longer.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(3)(a)(4))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1

Name:	us-gaap_ValueAddedTaxReceivableCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
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Period Type:	instant

Deferred costs, capitalized, prepaid, and other assets disclosure.

No definition available.

Name:	yq_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureLineItems
Namespace Prefix:	yq_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Amount, before allowance, of prepaid expenses and other current assets.

No definition available.

Name:	yq_PrepaidExpensesAndOtherCurrentAssetsGross
Namespace Prefix:	yq_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Prepaid other service fees.

No definition available.

Name:	yq_PrepaidOtherServiceFees
Namespace Prefix:	yq_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Amount, before allowance, of receivables for disposal of property and equipment.

No definition available.