Legal and Regulatory Matters - Turkish Regulation and Internal Investigation (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Loss Contingencies [Line Items]
Assets	$ 7,369,736		$ 7,369,736		$ 7,062,470
Liabilities	5,664,577		5,664,577		6,041,245
Revenues	1,277,439	$ 1,231,910	2,133,372	$ 2,138,444
Operating income (loss)	243,850	$ 210,568	180,983	$ 199,411
Variable Interest Entity, Primary Beneficiary
Loss Contingencies [Line Items]
Assets	1,340,653		1,340,653		1,309,113
Liabilities	405,181		405,181		424,297
Variable Interest Entity, Primary Beneficiary | Istanbul Bilgi University
Loss Contingencies [Line Items]
Required reimbursement, other activities					8,000
Assets	84,000		84,000		83,000
Liabilities	54,000		54,000		63,000
Revenues					106,000
Operating income (loss)					26,000
Depreciation and amortization					6,000
Variable Interest Entity, Primary Beneficiary | Istanbul Bilgi University | Consolidation Eliminations
Loss Contingencies [Line Items]
Due to related party	$ 28,000		$ 28,000		19,000
Variable Interest Entity, Primary Beneficiary | Management, Operational And Student Services, And Intellectual Property | Subsidiary of Common Parent | Istanbul Bilgi University
Loss Contingencies [Line Items]
Required reimbursement from related party					$ 29,000