v3.19.3.a.u2
COVER PAGE - USD ($)
 12 Months Ended
Dec. 31, 2019
Feb. 24, 2020
Jun. 28, 2019
Cover page.      
Document Type 10-K    
Document Annual Report true    
Document Period End Date Dec. 31, 2019    
Document Transition Report false    
Entity File Number 001-36376    
Entity Registrant Name 2U, INC.    
Entity Incorporation, State or Country Code DE    
Entity Tax Identification Number 26-2335939    
Entity Address, Address Line One 7900 Harkins Road    
Entity Address, City or Town Lanham,    
Entity Address, State or Province MD    
Entity Address, Postal Zip Code 20706    
City Area Code 301    
Local Phone Number 892-4350    
Title of 12(b) Security Common stock, $0.001 par value per share    
Trading Symbol TWOU    
Security Exchange Name NASDAQ    
Entity Well-known Seasoned Issuer Yes    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Interactive Data Current Yes    
Entity Filer Category Large Accelerated Filer    
Entity Small Business false    
Entity Emerging Growth Company false    
Entity Shell Company false    
Entity Public Float     $ 1,786,014,274
Entity Common Stock, Shares Outstanding   63,627,643  
Documents Incorporated by Reference
Portions of the Company’s definitive proxy statement, to be filed pursuant to Regulation 14A under the Securities Exchange Act of 1934, for its 2020 Annual Meeting of Stockholders, or an amendment on Form 10-K/A are incorporated by reference in Part III of this Form 10-K.
    
Entity Central Index Key 0001459417    
Amendment Flag false    
Current Fiscal Year End Date --12-31    
Document Fiscal Year Focus 2019    
Document Fiscal Period Focus FY