Dispositions (Details) $ in Thousands, $ in Thousands					12 Months Ended
	Feb. 12, 2019 USD ($)	Feb. 01, 2019 USD ($)	Jan. 25, 2018 USD ($)	Jan. 25, 2018 HKD ($)	Jan. 25, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
St. Augustine | Discontinued Operations, Disposed of by Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration received from dispositions		$ 400,000
LEI Lie Ying Limited | Discontinued Operations, Disposed of by Sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from second holdback payment			$ 9,100	$ 71,463
Amounts of material contingent liabilities remaining					$ 14,300
Gain (loss) on sale of business					$ 13,700
Receivables from sale of business, noncurrent						$ 25,900	$ 25,900
Exeter Street Holdings, LLC | St. Augustine | Discontinued Operations, Disposed of by Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of business		346,400
Net proceeds from dispositions		301,500
Other current assets disposed of		11,700
Accounts payable disposed of		58,100
Other current liabilities		7,200
Gain (loss) on sale of business		$ 223,500
Stamford International University | China YuHua Education Investment Limited
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration received from dispositions	$ 35,300
Number of campuses	0
Stamford International University | China YuHua Education Investment Limited | Affiliated Entity
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Debt assumed	$ 4,200
Stamford International University | LEI Singapore | Affiliated Entity
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of business	23,700
Net proceeds from dispositions	20,300
Net of debt assumed by purchaser	27,900
Gain (loss) on sale of business	$ 10,800