Summary of Significant Accounting Policies - Additional Information (Details) $ in Thousands			1 Months Ended		3 Months Ended		6 Months Ended
	Jan. 01, 2020 USD ($)	Jul. 01, 2018 USD ($)	Jul. 31, 2020 USD ($)	Jun. 30, 2020 USD ($) item	Jun. 30, 2020 USD ($) item	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) item segment	Jun. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Other assets				$ 1,794	$ 1,794		$ 1,794		$ 1,706
Number of operating segments | segment							1
Number of reporting units | segment							1
Unbilled revenue				7,275	7,275		$ 7,275
Amounts written off							0
Allowance for doubtful accounts				0	0		0
Lease liabilities				$ 45,192	$ 45,192		$ 45,192
Number of university partners | item				25	25		25
Accounts receivable credit losses							$ 0
Allowance for credit losses	$ 5,000			$ 5,000	$ 5,000		5,000
Retained earnings				1,455,907	1,455,907		1,455,907		1,341,344
Income tax expense					15,346	$ 14,125	$ 38,137	$ 25,581
Revenue Benchmark | Customer Concentration Risk
Summary Of Significant Accounting Policies [Line Items]
Concentration risk percentage							87.00%	89.70%
Computer Software
Summary Of Significant Accounting Policies [Line Items]
Estimated average useful life							3 years
Capitalized Content Development
Summary Of Significant Accounting Policies [Line Items]
Estimated average useful life							4 years
Other assets				$ 1,041	$ 1,041		$ 1,041
Interest Rate Corridor | 30 Day LIBOR equal to 1.5% through 3.0%
Summary Of Significant Accounting Policies [Line Items]
Interest rate spread on 30 Day LIBOR				1.50%	1.50%		1.50%
Interest Rate Corridor | 30 Day LIBOR exceeds 3.0%
Summary Of Significant Accounting Policies [Line Items]
Interest rate spread on 30 Day LIBOR				1.50%	1.50%		1.50%
Cash Flow Hedging
Summary Of Significant Accounting Policies [Line Items]
Effective portion of losses on derivatives included as a component of other comprehensive income, net of taxes							$ 341
Other Assets
Summary Of Significant Accounting Policies [Line Items]
Fair values of interest rate corridor instrument									$ 187
Minimum
Summary Of Significant Accounting Policies [Line Items]
Initial contract terms							7 years
Minimum | Interest Rate Corridor | 30 Day LIBOR equal to 1.5% through 3.0%
Summary Of Significant Accounting Policies [Line Items]
30 Day LIBOR index rate				1.50%	1.50%		1.50%
Minimum | Interest Rate Corridor | 30 Day LIBOR exceeds 3.0%
Summary Of Significant Accounting Policies [Line Items]
30 Day LIBOR index rate				3.00%	3.00%		3.00%
Maximum
Summary Of Significant Accounting Policies [Line Items]
Initial contract terms							15 years
Maximum | Interest Rate Corridor | 30-day LIBOR
Summary Of Significant Accounting Policies [Line Items]
30 Day LIBOR index rate				1.50%	1.50%		1.50%
Maximum | Interest Rate Corridor | 30 Day LIBOR equal to 1.5% through 3.0%
Summary Of Significant Accounting Policies [Line Items]
30 Day LIBOR index rate				3.00%	3.00%		3.00%
Grand Canyon University
Summary Of Significant Accounting Policies [Line Items]
Purchase price of assets		$ 870,097
Interest rate on Secured Note		6.00%
Term of additional lending to GCU for approved capital expenditures		3 years
Additional funding provided to GCU, net of repayments				$ 75,000			$ 169,815
Repayment of funding to GCU			$ 75,000
Master Services Agreement | Grand Canyon University
Summary Of Significant Accounting Policies [Line Items]
Percentage of tuition and fee revenue used for closing of purchase agreement		60.00%
Restatement Adjustment | ASU 2016-13
Summary Of Significant Accounting Policies [Line Items]
Allowance for credit losses	5,000
Retained earnings	(3,832)
Income tax expense	$ 1,168