Commitments and Contingencies - Standby Letters of Credit, Surety Bonds and Other Commitments (Details) € in Thousands		1 Months Ended	3 Months Ended
	Sep. 30, 2018 USD ($)	Nov. 30, 2016 USD ($)	Mar. 31, 2018 EUR (€)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2017 EUR (€)
Surety Bond
Debt Instrument [Line Items]
Guarantee amount, maximum potential amount of payments				$ 22,204,000	$ 13,980,000
Cash Collateralized Letter Of Credit - Spain Tax Audits
Debt Instrument [Line Items]
Letters of credit outstanding, amount				39,500,000	5,700,000
Non-Collateralized Surety Bond - UAM Brazil | Surety Bond
Debt Instrument [Line Items]
Guarantee amount, maximum potential amount of payments		$ 15,300,000
Cost of surety bond		$ 1,400,000
Guarantor obligation, term		P5Y
Kendall College, St. Augustine, Walden University, and NewSchool of Architecture and Design
Debt Instrument [Line Items]
Letters of credit outstanding, amount				$ 139,000,000	$ 136,900,000
Foreign Tax Authority | Tax Authority, Spain
Debt Instrument [Line Items]
Letters of credit outstanding, amount | €						€ 33,282
Income taxes paid	$ 33,800,000		€ 29,600