Acquisition Activity - Assets Acquired and Liabilities (Details) - USD ($) $ in Thousands	Sep. 01, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Assets acquired:
Intangible assets	$ 86,500
Liabilities assumed:
Goodwill		$ 243,486	$ 26,563	$ 26,563
Rasmussen
Business Acquisition [Line Items]
Cash and cash equivalents	329,000
Working capital adjustment and additional cash contributions	1,826
Total consideration	330,826
Assets acquired:
Cash and cash equivalents	5,200
Accounts receivable	10,700
Prepaid expenses	4,600
Property and equipment, net	36,996
Operating lease assets	75,800
Deferred tax asset	3,049
Intangible assets	86,500
Other assets	600
Total assets acquired	223,445
Liabilities assumed:
Accounts payable	1,200
Accrued expenses	6,142
Deferred revenue	22,700
Operating lease liabilities, current	11,200
Operating lease liabilities, long-term	67,000
Other liabilities	1,300
Total liabilities assumed	109,542
Net assets acquired	113,903
Goodwill	$ 216,923	$ 217,200