Represents the Company's adjusted quick ratio

No definition available.

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Namespace Prefix:	twou_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Ratio applied to covenants under the line of credit to incur additional indebtedness.

+ References

No definition available.

+ Details

Name:	twou_CovenantsRatio
Namespace Prefix:	twou_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of deferred government grant obligations due beyond one year or the operating cycle, whichever is longer.

+ References

No definition available.

+ Details

Name:	twou_DeferredGovernmentGrantObligationsNoncurrent
Namespace Prefix:	twou_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

N/A.

+ References

No definition available.

+ Details

Name:	twou_GovernmentGrantsAbstract
Namespace Prefix:	twou_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The minimum number of employees to employ at any time during the term of the loan or otherwise defaults on the loan, the entire principal balance, plus accrued interest, will become due and payable.

+ References

No definition available.

+ Details

Name:	twou_NumberOfEmployeesToEmployDuringTermOfLoanToAvoidRepaymentOfPrincipalBalanceAndAccruedInterestOfLoan
Namespace Prefix:	twou_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

The minimum number of employees to employ at any time during the term of the loan or otherwise defaults on the loan, the company will be required to repay a prorated portion of the loan plus interest.

+ References

No definition available.

+ Details

Name:	twou_NumberOfEmployeesToEmployDuringTermOfLoanToAvoidRepaymentOfProratedPortionOfLoanAndInterest
Namespace Prefix:	twou_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the number of government grants.

+ References

No definition available.

+ Details

Name:	twou_NumberOfGovernmentGrants
Namespace Prefix:	twou_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount represents the prorated portion of the loan amount per employee.

+ References

No definition available.

+ Details

Name:	twou_ProratedPortionOfLoanEmployee
Namespace Prefix:	twou_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentDescriptionOfVariableRateBasis
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

Name:	us-gaap_LineOfCredit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The effective interest rate during the reporting period.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityInterestRateDuringPeriod
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

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.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The amount of an asset, typically cash, provided to a counterparty to provide certain assurance of performance by the entity pursuant to the terms of a written or oral agreement, such as a lease.

+ References

+ Details

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

- Details

Name:	us-gaap_LineOfCreditFacilityAxis=twou_PrinceGeorgesCountyMarylandMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_StandbyLettersOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=twou_ShortCourseSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=twou_RevolvingWorkingCapitalFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=twou_HarkinsRoadLlcMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LineOfCreditFacilityAxis=twou_DepartmentOfCommerceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_BaseRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=twou_FederalFundRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=twou_ThirtyDaysLiborMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
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Period Type:

Debt (Details)			12 Months Ended
Debt (Details)	Jun. 27, 2017 USD ($) employee	Jun. 22, 2017 USD ($) employee	Dec. 31, 2017 USD ($)	Mar. 31, 2018 USD ($)	Jun. 30, 2017 USD ($) item	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2013 USD ($)
Lines of Credit
Aggregate borrowing base							$ 25,000,000	$ 37,000,000
Amount outstanding			$ 0			$ 0
Adjusted quick ratio			5.44			5.43
Security deposit			$ 11,500,000
Government Grants
Amount of loan			3,500,000		$ 3,500,000
Number of government grants \| item					2
Prince George's County, Maryland
Government Grants
Amount of loan		$ 1,500,000
Loan interest rate (in percentage)		3.00%
Minimum number of employees required to avoid default of loan for payment principal and accrued interest \| employee		650
Minimum number of employees required to avoid default of loan for payment prorated portion and interest \| employee		1,300
Amount of prorated portion of loan per employee		$ 2,252
Standby letters of credit
Lines of Credit
Aggregate borrowing base					$ 10,000,000
Short Course Segment
Lines of Credit
Amount outstanding			$ 0
Interest rate (in percentage)			10.25%
Short Course Segment \| Revolving working capital facility
Lines of Credit
Aggregate borrowing base			$ 1,900,000
Short Course Segment \| Revolving working capital facility \| Subsequent Event
Lines of Credit
Aggregate borrowing base				$ 1,300,000
Harkins Road LLC \| Department of Commerce
Government Grants
Amount of loan	$ 2,000,000
Loan interest rate (in percentage)	3.00%
Minimum number of employees required to avoid default of loan for payment principal and accrued interest \| employee	650
Minimum number of employees required to avoid default of loan for payment prorated portion and interest \| employee	1,600
Amount of prorated portion of loan per employee	$ 2,105
Base rate
Lines of Credit
Variable interest rate basis			Base rate
Applicable margin (as a percent)			1.50%
Federal fund rate
Lines of Credit
Variable interest rate basis			Federal fund rate
Applicable margin (as a percent)			1.00%
30 days LIBOR
Lines of Credit
Variable interest rate basis			30-day LIBOR
Applicable margin (as a percent)			1.00%
LIBOR
Lines of Credit
Variable interest rate basis			LIBOR
Applicable margin (as a percent)			2.50%
Minimum
Lines of Credit
Covenants ratio			1.10