Commitments and Contingencies - Summary of Redeemable Noncontrolling Interest (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
INTI Education Holdings Sdn Bhd
Redeemable Noncontrolling Interest [Line Items]
Noncontrolling interest, noncontrolling owners, ownership percent	10.10%
Pearl Retail Solutions Private Limited
Redeemable Noncontrolling Interest [Line Items]
Noncontrolling interest, noncontrolling owners, ownership percent	10.00%
Puttable common stock | INTI Education Holdings Sdn Bhd
Redeemable Noncontrolling Interest [Line Items]
Estimated Value as of September 30, 2018 redeemable within 12-months:	$ 9,016
Reported Value	9,016
Puttable common stock | Pearl Retail Solutions Private Limited
Redeemable Noncontrolling Interest [Line Items]
Estimated Value as of September 30, 2018 redeemable within 12-months:	1,880
Reported Value	1,880
Puttable preferred stock | Stamford International University
Redeemable Noncontrolling Interest [Line Items]
Estimated Value as of September 30, 2018 redeemable within 12-months:	62
Reported Value	62
Puttable non-controlling interest
Redeemable Noncontrolling Interest [Line Items]
Estimated Value as of September 30, 2018 redeemable within 12-months:	10,958
Reported Value	10,958
Puttable common stock - not currently redeemable
Redeemable Noncontrolling Interest [Line Items]
Estimated Value as of September 30, 2018 redeemable within 12-months:	0
Reported Value	1,713
Total redeemable noncontrolling interests and equity
Redeemable Noncontrolling Interest [Line Items]
Estimated Value as of September 30, 2018 redeemable within 12-months:	10,958
Reported Value	$ 12,671	$ 13,721