v3.10.0.1
Goodwill and Amortizable Intangible Assets - Amortizable Intangible Assets (Details) - USD ($)
$ in Thousands
9 Months Ended
Sep. 30, 2018
Dec. 31, 2017
Goodwill [Roll Forward]    
Beginning balance $ 71,988  
Foreign currency translation adjustments (9,033)  
Ending balance 62,955  
Gross Carrying Amount 180,102 $ 124,542
Accumulated Amortization (49,410) (33,781)
Net Carrying Amount 130,692 90,761
Capitalized technology    
Goodwill [Roll Forward]    
Gross Carrying Amount 63,789 27,108
Accumulated Amortization (14,593) (9,486)
Net Carrying Amount $ 49,196 17,622
Capitalized technology | Minimum    
Goodwill [Roll Forward]    
Estimated Average Useful Life (in years) 3 years  
Capitalized technology | Maximum    
Goodwill [Roll Forward]    
Estimated Average Useful Life (in years) 5 years  
Capitalized content development    
Goodwill [Roll Forward]    
Gross Carrying Amount $ 73,428 55,872
Accumulated Amortization (28,758) (21,417)
Net Carrying Amount $ 44,670 34,455
Capitalized content development | Minimum    
Goodwill [Roll Forward]    
Estimated Average Useful Life (in years) 4 years  
Capitalized content development | Maximum    
Goodwill [Roll Forward]    
Estimated Average Useful Life (in years) 5 years  
University client relationships    
Goodwill [Roll Forward]    
Estimated Average Useful Life (in years) 9 years  
Gross Carrying Amount $ 26,033 29,443
Accumulated Amortization (3,616) (1,636)
Net Carrying Amount $ 22,417 27,807
Trade names and domain names    
Goodwill [Roll Forward]    
Estimated Average Useful Life (in years) 10 years  
Gross Carrying Amount $ 16,852 12,119
Accumulated Amortization (2,443) (1,242)
Net Carrying Amount 14,409 10,877
In process capitalized technology and content development    
Goodwill [Roll Forward]    
Net Carrying Amount 32,400 $ 15,600
Graduate Program Segment    
Goodwill [Roll Forward]    
Beginning balance 0  
Foreign currency translation adjustments 0  
Ending balance 0  
Short Course Segment    
Goodwill [Roll Forward]    
Beginning balance 71,988  
Foreign currency translation adjustments (9,033)  
Ending balance $ 62,955