v3.8.0.1

Related Party Transactions (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Related Party Transactions |  |  |
Repayment of security deposit | $ 0.1 |  |
Rental income from related entity |  | $ 0.3 | $ 0.3
Executive Officer |  |  |
Related Party Transactions |  |  |
Expenses incurred related to the services received from related party | $ 0.0 | $ 1.4 | $ 1.7
Minimum |  |  |
Related Party Transactions |  |  |
Ownership interest (as percent) |  | 5.00% | 5.00%

X
- Definition Represents the percentage of ownership in an entity. + References No definition available. + Details
Name: | twou_OwnershipInterest
Namespace Prefix: | twou_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the information about rental income received from the related entity. + References No definition available. + Details
Name: | twou_RentalIncomeFromRelatedParties
Namespace Prefix: | twou_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The repayment amount of security deposit from related party in connection with expiration of the sublease. + References No definition available. + Details
Name: | twou_RepaymentOfSecurityDepositFromRelatedParty
Namespace Prefix: | twou_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Expenses recognized resulting from transactions (excluding transactions that are eliminated in consolidated or combined financial statements) with related party. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 850 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864 + Details
Name: | us-gaap_RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition 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. + References No definition available. + Details
Name: | us-gaap_RelatedPartyTransactionLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=us-gaap_ExecutiveOfficerMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |