Equity Awards - Stock-based compensation (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Schedule of stock-based compensation expense
Stock-based compensation expense included in operating expense	$ 3,566	$ 3,250	$ 6,576	$ 5,937
Tax benefit	923	894	1,682	1,646
Stock-based compensation expense, net of tax	2,643	2,356	4,894	4,291
Instructional and support costs
Schedule of stock-based compensation expense
Stock-based compensation expense included in operating expense	1,017	499	1,875	1,118
General and administration
Schedule of stock-based compensation expense
Stock-based compensation expense included in operating expense	2,138	2,751	3,811	4,819
Merger and integration costs
Schedule of stock-based compensation expense
Stock-based compensation expense included in operating expense	$ 411	$ 0	$ 890	$ 0

The amount of expense, net of income tax, recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

No definition available.

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No definition available.

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- Definition

The total recognized tax benefit related to compensation cost for equity-based payment arrangements recognized in income during the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(1)(i)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

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- Definition

The aggregate amount of noncash, equity-based employee remuneration. This may include the value of stock or unit options, amortization of restricted stock or units, and adjustment for officers' compensation. As noncash, this element is an add back when calculating net cash generated by operating activities using the indirect method.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

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