Legal and Regulatory Matters - Turkish Regulation and Internal Investigation (Details) ₺ in Thousands, $ in Thousands		3 Months Ended										12 Months Ended
	Nov. 04, 2016 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2014 TRY (₺)	Dec. 31, 2017 USD ($) license	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Loss Contingencies [Line Items]
Assets		$ 7,391,723				$ 7,062,470						$ 7,391,723	$ 7,062,470
Liabilities		5,390,444				6,041,245						5,390,444	6,041,245
Revenues		1,261,223	$ 983,394	$ 1,277,439	$ 855,933	1,175,893	$ 929,855	$ 1,231,910	$ 906,534			4,377,989	4,244,192	$ 4,291,659
Operating income		181,499	$ (5,696)	$ 243,850	$ (62,866)	170,980	$ 12,502	$ 210,568	$ (11,157)			356,787	382,893	336,957
Kendall College, St. Augustine, Walden University, and NewSchool of Architecture and Design
Loss Contingencies [Line Items]
Letters of credit outstanding, amount		136,900				105,600						136,900	105,600
Variable Interest Entity, Primary Beneficiary
Loss Contingencies [Line Items]
Assets		1,419,579				1,309,113						1,419,579	1,309,113
Liabilities		449,561				424,297						449,561	424,297
Revenues												$ 123,237	113,276	$ 106,005
Variable Interest Entity, Primary Beneficiary | Istanbul Bilgi University
Loss Contingencies [Line Items]
Number of licenses canceled by higher education council (license) | license												15
Charitable contributions	$ 13,000									$ 18,000	₺ 40,000
Required reimbursement from related party													29,000
Required reimbursement, other activities													8,000
Assets		112,000				83,000						$ 112,000	83,000
Liabilities		84,000				63,000						84,000	63,000
Revenues												101,000	106,000
Operating income												28,000	26,000
Depreciation and amortization												6,000	6,000
Variable Interest Entity, Primary Beneficiary | Istanbul Bilgi University | Consolidation Eliminations
Loss Contingencies [Line Items]
Due to related party		$ 37,000				$ 19,000						$ 37,000	$ 19,000