Acquisitions (Acquired Intangible Assets Subject to Amortization and Values and Estimated Useful Lives) (Detail) - OnCourse Learning [Member] $ in Thousands		1 Months Ended
	May 31, 2019 USD ($)	May 31, 2019 USD ($)
Business Acquisition [Line Items]
Amortizable intangible assets, estimated useful lives	9 years
Customer Relationships [Member]
Business Acquisition [Line Items]
Intangible assets, finite lived	$ 26,400	$ 26,400
Amortizable intangible assets, estimated useful lives		11 years
Curriculum/Software [Member]
Business Acquisition [Line Items]
Intangible assets, finite lived	11,600	$ 11,600
Amortizable intangible assets, estimated useful lives		6 years
Course Delivery Technology
Business Acquisition [Line Items]
Intangible assets, finite lived	$ 6,700	$ 6,700
Amortizable intangible assets, estimated useful lives		5 years