Legal and Regulatory Matters - Brazilian Regulation (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2019 USD ($) educational_institution	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Loss Contingencies [Line Items]
Revenues	$ 883,152	$ 773,699	$ 992,403	$ 601,072	$ 892,451	$ 778,255	$ 1,005,229	$ 614,278	$ 3,250,326	$ 3,290,213	$ 3,333,073
Brazil
Loss Contingencies [Line Items]
Number of postsecondary educational institutions (educational institution) | educational_institution									12
Percentage of students enrolled in government programs									7.00%	11.00%
Percentage of funds received									13.00%	20.00%
Revenues									$ 578,433	$ 654,070	765,358
Brazil | Grant
Loss Contingencies [Line Items]
Revenues									$ 100,600	$ 112,500	$ 115,200