Discontinued Operations and Assets Held for Sale - Schedule of carrying amounts of the major classes of assets and liabilities classified as held for sale (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total assets held for sale	$ 389,773	$ 1,372,883
Total liabilities held for sale	189,118	680,383
Discontinued Operations, Held-for-sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash and cash equivalents	55,401	215,644
Receivables, net	14,762	62,576
Property and equipment, net	182,530	671,121
Goodwill	9,753	131,329
Tradenames	6,890	124,932
Operating lease right-of-use assets, net	59,231	0
Other assets	52,730	106,326
Total assets held for sale	381,297	1,311,928
Deferred revenue and student deposits	14,287	115,969
Operating leases, including current portion	63,304	0
Long-term debt, including current portion	55,495	279,612
Other liabilities	56,032	269,558
Total liabilities held for sale	189,118	665,139
Disposal Group, Held-for-sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total assets held for sale	8,476	60,955
UniNorte Brazil | Disposal Group, Held-for-sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Receivables, net	0	6,983
Property and equipment, net	0	16,726
Goodwill	0	15,165
Tradenames	0	8,146
Other assets	0	13,935
Deferred revenue and student deposits	0	469
Long-term debt, including current portion	0	5,370
Other liabilities	0	9,405
Total liabilities held for sale	0	15,244
Other Land and Buildings | Disposal Group, Held-for-sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Property and equipment, net	$ 8,476	$ 0