Revenue from Contracts with Customers Revenue from Contracts with Customers (Narrative 2) (Details) - Long-term Contract with Customer [Member] - Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-04-01 $ in Millions	Mar. 31, 2020 USD ($)
Kaplan International [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 9.7
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	2 years
Test Preparation [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 9.3
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	12 months