Amount of assets including goodwill acquired at the acquisition date.

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Amount of investments in debt securities available-for-sale expected to be converted to cash, sold or exchanged within one year or the normal operating cycle, if longer, acquired at the acquisition date.

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Amount of accounts payable and accrued expenses due within one year or within the normal operating cycle, if longer, assumed at the acquisition date.

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Amount of contract with customer liability due within one year or within the normal operating cycle, if longer, assumed at the acquisition date.

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The amount of income tax receivable recognized as of the acquisition date.

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Amount of investments in debt securities available-for-sale expected to be converted to cash, sold or exchanged after one year or the normal operating cycle, if longer, acquired at the acquisition date.

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Amount of currency on hand as well as demand deposits with banks or financial institutions, acquired at the acquisition date. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Amount of other assets expected to be realized or consumed before one year or the normal operating cycle, if longer, acquired at the acquisition date.

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Amount due from customers or clients for goods or services, including trade receivables, that have been delivered or sold in the normal course of business, and amounts due from others, including related parties expected to be converted to cash, sold or exchanged within one year or the normal operating cycle, if longer, acquired at the acquisition date.

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Amount of deferred tax liability attributable to taxable temporary difference assumed at the acquisition date that are classified as noncurrent.

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Amount of intangible assets, excluding goodwill, acquired at the acquisition date.

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Amount of liabilities assumed at the acquisition date.

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Amount of other liabilities due after one year or the normal operating cycle, if longer, assumed at the acquisition date.

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Amount of other assets expected to be realized or consumed after one year or the normal operating cycle, if longer, acquired at the acquisition date.

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The amount of property, plant, and equipment recognized as of the acquisition date.

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Amount recognized for assets, including goodwill, in excess of (less than) the aggregate liabilities assumed.

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Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Business Combinations - Preliminary Fair Value of Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Aug. 01, 2018	Dec. 31, 2017	Dec. 31, 2016
Preliminary fair value of assets and liabilities
Goodwill	$ 732,540		$ 20,744	$ 20,744
Capella Merger
Preliminary fair value of assets and liabilities
Cash and cash equivalents		$ 167,859
Marketable securities, current		31,419
Tuition receivable		39,141
Income tax receivable		163
Other current assets		8,496
Marketable securities, non-current		34,700
Property and equipment, net		53,182
Other assets		14,556
Intangible assets		349,800
Goodwill		725,740
Total assets acquired		1,425,056
Accounts payable and accrued expenses		(46,735)
Contract liabilities		(39,000)
Deferred income taxes		(100,123)
Other long term liabilities		(2,237)
Total liabilities assumed		(188,095)
Total consideration		$ 1,236,961