Merger with Capella Education Company - Preliminary Fair Value of Assets and Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Aug. 01, 2018	Dec. 31, 2017
Preliminary fair value of assets and liabilities
Goodwill	$ 730,729		$ 20,744
Capella Merger
Preliminary fair value of assets and liabilities
Cash and cash equivalents		$ 168,387
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		15,906
Intangible assets		349,800
Goodwill		723,929
Total assets acquired		1,425,123
Accounts payable and accrued expenses		(46,735)
Contract liabilities		(39,000)
Deferred income taxes		(100,190)
Other long term liabilities		(2,237)
Total liabilities assumed		(188,162)
Total consideration		$ 1,236,961