REVENUE AND DEFERRED REVENUE - Schedule of Deferred Revenue by Reportable Segment (Details)	Mar. 31, 2020 USD ($)
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Performance obligations	$ 164,005
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2020-04-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Performance obligations	$ 105,969
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	9 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2021-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Performance obligations	$ 32,239
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	2 years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2023-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Performance obligations	$ 4,946
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	2 years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2025-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Performance obligations	$ 20,851
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period
Literacy
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Performance obligations	$ 41,256
Literacy | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2020-04-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Performance obligations	$ 32,782
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	9 months
Literacy | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2021-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Performance obligations	$ 8,089
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	2 years
Literacy | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2023-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Performance obligations	$ 381
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	2 years
Literacy | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2025-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Performance obligations	$ 4
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period
E&E Language
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Performance obligations	$ 55,065
E&E Language | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2020-04-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Performance obligations	$ 33,498
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	9 months
E&E Language | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2021-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Performance obligations	$ 8,961
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	2 years
E&E Language | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2023-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Performance obligations	$ 2,743
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	2 years
E&E Language | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2025-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Performance obligations	$ 9,863
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period
Consumer Language
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Performance obligations	$ 67,684
Consumer Language | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2020-04-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Performance obligations	$ 39,689
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	9 months
Consumer Language | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2021-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Performance obligations	$ 15,189
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	2 years
Consumer Language | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2023-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Performance obligations	$ 1,822
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	2 years
Consumer Language | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2025-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Performance obligations	$ 10,984
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period