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Revenue - Additional Information (Details) - USD ($)
Sep. 30, 2019
Dec. 31, 2018
Capitalized Contract Cost [Line Items]    
Contract assets $ 0 $ 0
Deferred revenue and student deposits 20,608,000 18,310,000
Students deposits   8,400,000
Courses and Terms in Progress    
Capitalized Contract Cost [Line Items]    
Future revenue 11,900,000  
Future Courses and Terms    
Capitalized Contract Cost [Line Items]    
Future revenue   $ 9,900,000
Students deposits $ 8,700,000