v3.10.0.1
Segment and Geographic Information - Revenue and Total Assets by Segment (Details) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Sep. 30, 2018
Sep. 30, 2017
Sep. 30, 2018
Sep. 30, 2017
Dec. 31, 2017
Segment Information          
Total segment revenue $ 106,963 $ 70,250 $ 296,674 $ 200,074  
Total segment profitability $ 4,675 $ (3,720) $ (2,402) $ (1,309)  
Total segment profitability margin 4.40% (5.30%) (0.80%) (0.70%)  
Net loss $ (9,944) $ (14,739) $ (43,162) $ (29,932)  
Adjustments          
Interest income (1,799) (18) (3,053) (267)  
Interest expense 27 36 81 37  
Foreign currency loss (gain) 273 (59) 1,493 972  
Depreciation and amortization expense 8,599 5,887 23,382 13,318  
Income tax benefit (414) (974) (5,207) (974)  
Stock-based compensation expense 7,933 6,147 24,064 15,537  
Total adjustments 14,619 11,019 40,760 28,623  
Total assets 811,491   811,491   $ 482,062
Trade accounts receivable          
Accounts receivable, net 49,651   49,651   14,174
Total trade accounts receivable 49,415   49,415   14,174
Contract liabilities 18,953   18,953   7,024
Intersegment Eliminations          
Segment Information          
Total segment revenue 44   44    
Graduate Program Segment          
Segment Information          
Total segment revenue 89,719 65,924 251,487 195,748  
Total segment profitability $ 5,564 $ (718) $ (615) $ 1,693  
Total segment profitability margin 5.20% (1.00%) (0.20%) 0.80%  
Adjustments          
Total assets $ 700,978   $ 700,978   359,597
Trade accounts receivable          
Accounts receivable, net 22,397   22,397   12,520
Graduate Program Segment unbilled revenue 25,583   25,583   666
Contract liabilities 9,607   9,607   2,523
Deferred revenue reclassified to revenue 0   2,500    
Contract Acquisition Costs          
Capitalized contract acquisition costs     300    
Short Course Segment          
Segment Information          
Total segment revenue 17,244 $ 4,326 45,187 $ 4,326  
Total segment profitability $ (889) $ (3,002) $ (1,787) $ (3,002)  
Total segment profitability margin (0.80%) (4.30%) (0.60%) (1.50%)  
Adjustments          
Total assets $ 110,513   $ 110,513   122,465
Trade accounts receivable          
Accounts receivable, net 1,435   1,435   988
Contract liabilities 9,346   9,346   4,501
Deferred revenue reclassified to revenue 0   4,500    
Non-US | Short Course Segment          
Segment Information          
Total segment revenue 8,800   26,000    
Contract Acquisition Costs          
Long-lived assets $ 1,300 $ 3,000 $ 1,300 $ 3,000 $ 700