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Amount, after allowance for credit loss, of right to consideration in exchange for good or service transferred to customer when right is conditioned on something other than passage of time, classified as noncurrent.

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Amount of revenue recognized that was previously included in balance of obligation to transfer good or service to customer for which consideration from customer has been received or is due.

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Amount of deferred income and obligation to transfer product and service to customer for which consideration has been received or is receivable.

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Amount of revenue recognized that was previously reported as deferred or unearned revenue.

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Revenue from Contracts with Customers (Narrative) (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended
	Apr. 30, 2020	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Disaggregation of Revenue [Line Items]
Deferred revenue recognized in period related to beginning balance				$ 271,900
Deferred Revenue		$ 287,681		287,681		$ 363,065
CARES Act relief from COVID-19 [Member] \| Medicare Accelerated Advanced Payment Program Relief Fund [Member] \| Graham Healthcare Group [Member]
Disaggregation of Revenue [Line Items]
Government Relief, CARES Act	$ 31,500
Deferred revenue recognized		5,600	$ 5,000	12,000	$ 5,000
Deferred Revenue		$ 500		$ 500
Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Percentage of Revenue		60.00%	66.00%	60.00%	68.00%
Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Percentage of Revenue		40.00%	34.00%	40.00%	32.00%
U.S. [Member]
Disaggregation of Revenue [Line Items]
Percentage of Revenue		79.00%	78.00%	79.00%	77.00%
Non-US [Member]
Disaggregation of Revenue [Line Items]
Percentage of Revenue		21.00%	22.00%	21.00%	23.00%
Kaplan International [Member]
Disaggregation of Revenue [Line Items]
Contract with Customer, Asset, Net, Noncurrent		$ 19,000		$ 19,000		$ 17,700
Supplemental Education [Member] \| Long-term Contract with Customer [Member]
Disaggregation of Revenue [Line Items]
Minimum Term of Contract				12 months
Revenue Remaining Performance Obligation Percentage of Revenue Expected to be Recognized Over Next 12 Months		75.00%		75.00%