Average borrowings outstanding during the period, both short and long term.

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Minimum consolidated interest coverage ratio based upon the ratio of consolidated adjusted EBITDA to consolidated interest expense as determined pursuant to the Credit Agreement.

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Maximum net leverage ratio required to be maintained under Credit Agreement.

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Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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Face (par) amount of debt instrument at time of issuance.

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Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

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The average effective interest rate during the reporting period.

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Contractual interest rate for funds borrowed, under the debt agreement.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount of the required periodic payments applied to principal.

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Percentage of principal amount of debt redeemed.

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Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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The percentage points added to the reference rate to compute the variable rate on the interest rate derivative.

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Fixed interest rate related to the interest rate derivative.

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Nominal or face amount used to calculate payment on derivative.

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Gross amount of debt extinguished.

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Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

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Amount of the cost of borrowed funds accounted for as interest expense.

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The net amount of operating interest income (expense).

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Amount before accretion (amortization) of purchase discount (premium) of interest income on nonoperating securities.

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The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

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The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

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Including the current and noncurrent portions, carrying value as of the balance sheet date of loans from a bank with maturities initially due after one year or beyond the normal operating cycle if longer.

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The interest rate applicable to the portion of the carrying amount of long-term borrowings outstanding as of the balance sheet date, including current maturities, which accrues interest at a set, unchanging rate.

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Including the current and noncurrent portions, the carrying value as of the balance sheet date of notes payable to banks, excluding mortgage notes, initially due beyond one year or beyond the operating cycle if longer.

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Including the current and noncurrent portions, carrying value as of the balance sheet date of uncollateralized debt obligations (with maturities initially due after one year or beyond the operating cycle if longer).

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Debt (Narrative) (Details)						1 Months Ended	3 Months Ended								12 Months Ended
Debt (Narrative) (Details)	Dec. 02, 2019 USD ($)	Jan. 31, 2019 USD ($)	Jun. 29, 2018 USD ($)	May 30, 2018 USD ($)	Jul. 14, 2016 GBP (£)	Jun. 30, 2018 USD ($)	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Jul. 25, 2016 GBP (£)
Debt Instrument [Line Items]
Line of Credit							$ 0				$ 0				$ 0	$ 0
Debt extinguishment costs											0	$ 0	$ (11,378,000)	$ 0	0	(11,378,000)	$ 0
Average borrowings outstanding															$ 500,600,000	$ 517,200,000
Weighted average interest rate of borrowings															5.10%	5.60%
Interest expense															$ (23,628,000)	$ (32,549,000)	(27,305,000)
Interest expense							7,192,000	$ 6,776,000	$ 8,386,000	$ 7,425,000	6,531,000	6,135,000	17,165,000	8,071,000	29,779,000	37,902,000	33,886,000
Interest income							$ 1,398,000	$ 1,474,000	$ 1,579,000	$ 1,700,000	$ 1,469,000	$ 611,000	$ 1,901,000	$ 1,372,000	$ 6,151,000	$ 5,353,000	6,581,000
7.25% Unsecured Notes due February 1, 2019 [Member]
Debt Instrument [Line Items]
Interest rate			7.25%				7.25%				7.25%				7.25%	7.25%
Redemption of notes outstanding			$ 400,000,000
Debt extinguishment costs			$ 11,400,000
Other Indebtedness [Member]
Debt Instrument [Line Items]
Interest rate							2.00%				2.00%				2.00%	2.00%
5.75% Unsecured Notes due June 1, 2026 [Member]
Debt Instrument [Line Items]
Unamortized debt issuance costs							$ 4,600,000				$ 5,300,000				$ 4,600,000	$ 5,300,000
Interest rate				5.75%
Debt instrument, face amount				$ 400,000,000
Fair value of debt instrument							427,700,000				406,700,000				427,700,000	406,700,000
Carrying value of debt instrument							395,393,000				394,675,000				395,393,000	394,675,000
Kaplan Four Year Credit Agreement Dated July 14, 2016 [Member]
Debt Instrument [Line Items]
Unamortized debt issuance costs							100,000				200,000				100,000	200,000
Line of Credit							78,650,000				82,366,000				78,650,000	82,366,000
Five-Year Credit Agreement dated May 30, 2018 [Member]
Debt Instrument [Line Items]
Debt Instrument, Term				5 years
Credit facility current borrowing capacity				$ 300,000,000
Debt covenant net leverage ratio, maximum				3.5
Debt covenant interest coverage ratio, minimum				3.5
Multicurrency $100 million portion of revolver [Member]
Debt Instrument [Line Items]
Credit facility current borrowing capacity				$ 100,000,000
USD $200 million portion of revolver [Member]
Debt Instrument [Line Items]
Credit facility current borrowing capacity				$ 200,000,000
Pinnacle Bank Term Loan [Member]
Debt Instrument [Line Items]
Loans Payable to Bank							11,203,000				0				11,203,000	0
Commercial note with SunTrust [Member]
Debt Instrument [Line Items]
Notes Payable to Bank							$ 27,500,000				$ 0				27,500,000	$ 0
Minimum [Member] \| Five-Year Credit Agreement dated May 30, 2018 [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage				0.15%
Maximum [Member] \| Five-Year Credit Agreement dated May 30, 2018 [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage				0.25%
Eurodollar [Member] \| Five-Year Credit Agreement dated May 30, 2018 [Member]
Debt Instrument [Line Items]
Applicable interest rate margin				1.00%
Fed Funds Effective Rate Overnight Index Swap Rate [Member] \| Five-Year Credit Agreement dated May 30, 2018 [Member]
Debt Instrument [Line Items]
Applicable interest rate margin				0.50%
Education [Member] \| Interest Rate Swap [Member]
Debt Instrument [Line Items]
Derivative, Notional Amount \| £																		£ 75,000,000
Derivative, Fixed Interest Rate																		0.51%
Basis Spread on Variable Rate																		1.50%
Interest rate swap percentage rate																		2.01%
Education [Member] \| Kaplan Four Year Credit Agreement Dated July 14, 2016 [Member]
Debt Instrument [Line Items]
Line of Credit \| £					£ 75,000,000
Debt Instrument, Term					4 years
Credit facility current borrowing capacity \| £																		£ 75,000,000
Debt covenant net leverage ratio, maximum					3.5
Debt covenant interest coverage ratio, minimum					3.5
Education [Member] \| London Interbank Offered Rate (LIBOR) [Member] \| Minimum [Member] \| Kaplan Four Year Credit Agreement Dated July 14, 2016 [Member]
Debt Instrument [Line Items]
Applicable interest rate margin					1.25%
Education [Member] \| London Interbank Offered Rate (LIBOR) [Member] \| Maximum [Member] \| Kaplan Four Year Credit Agreement Dated July 14, 2016 [Member]
Debt Instrument [Line Items]
Applicable interest rate margin					1.75%
Graham Healthcare Group [Member]
Debt Instrument [Line Items]
Interest expense						$ 6,200,000
Graham Healthcare Group [Member] \| Pinnacle Bank Term Loan [Member]
Debt Instrument [Line Items]
Interest rate	4.35%
Loans Payable to Bank	$ 11,250,000
Debt Instrument, Term	5 years
Graham Healthcare Group [Member] \| Pinnacle Bank Line Of Credit [Member]
Debt Instrument [Line Items]
Line of Credit	$ 2,250,000
Debt Instrument, Term	2 years
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.25%
Applicable interest rate margin	2.75%
Debt Instrument, Redemption, First Anniversary [Member] \| Education [Member] \| Kaplan Four Year Credit Agreement Dated July 14, 2016 [Member]
Debt Instrument [Line Items]
Debt Instrument Price Percentage Of Outstanding Balance Redeemed					6.66%
Debt Instrument, Redemption, Second Anniversary [Member] \| Education [Member] \| Kaplan Four Year Credit Agreement Dated July 14, 2016 [Member]
Debt Instrument [Line Items]
Debt Instrument Price Percentage Of Outstanding Balance Redeemed					6.66%
Debt Instrument, Redemption, Third Anniversary [Member] \| Education [Member] \| Kaplan Four Year Credit Agreement Dated July 14, 2016 [Member]
Debt Instrument [Line Items]
Debt Instrument Price Percentage Of Outstanding Balance Redeemed					6.66%
Securities Subject to Mandatory Redemption [Member]
Debt Instrument [Line Items]
Interest income															$ 100,000		$ 2,300,000
Automotive [Member] \| Interest Rate Swap [Member]
Debt Instrument [Line Items]
Derivative, Notional Amount		$ 30,000,000
Derivative, Fixed Interest Rate		2.70%
Basis Spread on Variable Rate		2.00%
Interest rate swap percentage rate		4.70%
Automotive [Member] \| Commercial note with SunTrust [Member]
Debt Instrument [Line Items]
Debt Instrument, Term		10 years
Notes Payable to Bank		$ 30,000,000
Debt Instrument, Periodic Payment, Principal		$ 250,000
Automotive [Member] \| London Interbank Offered Rate (LIBOR) [Member] \| Minimum [Member] \| Commercial note with SunTrust [Member]
Debt Instrument [Line Items]
Applicable interest rate margin		1.75%
Automotive [Member] \| London Interbank Offered Rate (LIBOR) [Member] \| Maximum [Member] \| Commercial note with SunTrust [Member]
Debt Instrument [Line Items]
Applicable interest rate margin		2.00%