Acquisitions - Schedule of Components of Identifiable Intangible Assets Acquired and their Estimated Useful Lives (Detail) - USD ($) $ in Thousands		9 Months Ended
	Feb. 12, 2015	Sep. 30, 2015
Publishing content
Acquired Finite-Lived Intangible Assets [Line Items]
Useful Life in Years		3 years
Studer Group
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible Asset	$ 97,500
Studer Group | Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible Asset	$ 42,400
Useful Life in Years	9 years
Studer Group | Customer contracts
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible Asset	$ 25,100
Useful Life in Years	4 years
Studer Group | Trade names
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible Asset	$ 22,800
Useful Life in Years	5 years
Studer Group | Technology and software
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible Asset	$ 3,900
Useful Life in Years	3 years
Studer Group | Publishing content
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible Asset	$ 3,300
Useful Life in Years	3 years