Segment and Geographic Information - Segment Performance (Details) - USD ($) $ in Thousands |
3 Months Ended | 12 Months Ended | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Dec. 31, 2017 |
Sep. 30, 2017 |
Jun. 30, 2017 |
Mar. 31, 2017 |
Dec. 31, 2016 |
Sep. 30, 2016 |
Jun. 30, 2016 |
Mar. 31, 2016 |
Dec. 31, 2017 |
Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
|
| Revenue by segment | ||||||||||||
| Total segment revenue | $ 86,678 | $ 70,250 | $ 64,995 | $ 64,829 | $ 57,350 | $ 51,960 | $ 49,110 | $ 47,444 | $ 286,752 | $ 205,864 | $ 150,194 | |
| Profitability by Segment | ||||||||||||
| Total Segment Profitability | $ 11,416 | $ 4,541 | $ (6,629) | |||||||||
| Segment profitability margin | ||||||||||||
| Total segment profitability margin (in percent) | 4.00% | 2.00% | (4.00%) | |||||||||
| Net loss | ||||||||||||
| Net loss | 509 | (14,739) | (11,754) | (3,439) | (2,209) | (6,758) | (8,337) | (3,380) | $ (29,423) | $ (29,423) | $ (20,684) | $ (26,733) |
| Adjustments | ||||||||||||
| Interest income | (104) | (18) | (53) | $ (196) | (163) | $ (37) | (91) | (92) | (371) | (383) | (167) | |
| Interest expense | 50 | 36 | $ 1 | $ 9 | $ 26 | 87 | 35 | 552 | ||||
| Foreign currency loss | 866 | |||||||||||
| Depreciation and amortization expense | 19,624 | 9,750 | 7,220 | |||||||||
| Income tax benefit | (323) | $ (974) | (1,297) | |||||||||
| Stock-based compensation expense | 21,930 | 15,823 | 12,499 | |||||||||
| Total adjustments | 40,839 | 25,225 | 20,104 | |||||||||
| Total assets | ||||||||||||
| Total assets | 482,062 | 244,320 | 482,062 | 482,062 | 244,320 | |||||||
| Graduate Program Segment | ||||||||||||
| Revenue by segment | ||||||||||||
| Total segment revenue | 270,432 | 205,864 | 150,194 | |||||||||
| Profitability by Segment | ||||||||||||
| Total Segment Profitability | $ 13,022 | $ 4,541 | $ (6,629) | |||||||||
| Segment profitability margin | ||||||||||||
| Total segment profitability margin (in percent) | 5.00% | 2.00% | (4.00%) | |||||||||
| Total assets | ||||||||||||
| Total assets | 359,597 | $ 244,320 | 359,597 | $ 359,597 | $ 244,320 | |||||||
| Short Course Segment | ||||||||||||
| Revenue by segment | ||||||||||||
| Total segment revenue | 16,320 | |||||||||||
| Profitability by Segment | ||||||||||||
| Total Segment Profitability | $ (1,606) | |||||||||||
| Segment profitability margin | ||||||||||||
| Total segment profitability margin (in percent) | (1.00%) | |||||||||||
| Total assets | ||||||||||||
| Total assets | $ 122,465 | $ 122,465 | $ 122,465 | |||||||||