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Fair value of company common stock

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Number of contingently issuable shares in stock award

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Right To Elect Board Of Directors Percentage

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The grant-date fair value of stock awards granted during the reporting period as calculated by applying the disclosed pricing methodology.

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The weighted average price as of the end of the year at which grantees can acquire the shares reserved for issuance under the stock option plan which are not vested.

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Options outstanding exercisable now.

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Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number Exercisable Year Five

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Options outstanding exercisable in year four.

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Options outstanding exercisable in year one.

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Options outstanding exercisable in year three.

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Options outstanding exercisable in year two.

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Share Based Compensation Arrangement By Share Based Payment Award Options Unvested Intrinsic Value

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The weighted average period between the balance sheet date and expiration for all awards outstanding but not vested under the plan, which may be expressed in a decimal value for number of years.

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Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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Aggregate number of common shares reserved for future issuance.

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Aggregate dividends declared during the period for each share of common stock outstanding.

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Amount of distribution made to individual in accordance with deferred compensation arrangement.

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Aggregate carrying value as of the balance sheet date of the liabilities for stock option plans and other equity-based compensation arrangements.

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Amount of cost not yet recognized for nonvested award under share-based payment arrangement.

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Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Amount of tax benefit from exercise of option under share-based payment arrangement.

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The cash outflow to reacquire common stock during the period.

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Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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Number of shares authorized for issuance under share-based payment arrangement.

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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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Gross number of share options (or share units) granted during the period.

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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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Number of options outstanding, including both vested and non-vested options.

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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Number of non-vested options outstanding.

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Number of share options (or share units) exercised during the current period.

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The number of shares authorized to be repurchased by an entity's Board of Directors under a stock repurchase plan.

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The remaining number of shares authorized to be repurchased by an entity's Board of Directors under a stock repurchase plan.

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Capital Stock, Stock Awards, and Stock Options (Narrative) (Details) - USD ($)	1 Months Ended	12 Months Ended
	Jan. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Sep. 10, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Cost of shares repurchased by company		$ 71,386,000	$ 55,683,000	$ 161,829,000
Shares subject to award outstanding		27,218	31,571
Number of shares forfeited due to modification		4,353
Number of shares awarded		1,221
Exercised, Number of Shares		5,084
Number of shares granted		0
Stock options outstanding		178,105	183,189
Dividends declared per common share		$ 6.32	$ 6.04	$ 5.80
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period		1,221
Kaplan Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercised, Number of Shares		0	0	0
Number of shares granted		0	0	0
Stock options outstanding		0
Share-based Payment Arrangement, Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares excluded from earnings per share		105,000	104,000	181,258
Maximum [Member] \| Kaplan Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period		5 years
Minimum [Member] \| Kaplan Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period		4 years
Education [Member] \| Kaplan Stock Option and Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense (credit)		$ 1,000,000	$ 1,300,000	$ (1,100,000)
Accrual balance related to stock based compensation		11,300,000
Stock compensation payouts		$ 0	$ 0	$ 0
Class B Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Right to elect Board of Directors percentage		30.00%
Shares repurchased by company		121,761	93,969	406,112
Cost of shares repurchased by company		$ 71,400,000	$ 55,700,000	$ 161,800,000
Number of shares authorized to be repurchased					500,000
Authorized shares remaining for repurchase		148,421
Market value of company's stock (in dollars per share)		$ 604.21
Class B Common Stock [Member] \| Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share awards outstanding, restriction will lapse in 2023		11,120
Share awards outstanding, restriction will lapse in 2025		14,098
Stock-based compensation expense (credit)		$ 3,400,000	3,900,000	4,100,000
Total unrecognized compensation expense		$ 4,600,000
Years over which cost expected to be recognized		1 year 4 months 24 days
Share awards outstanding, restriction will lapse in 2027		2,000
Class B Common Stock [Member] \| Share-based Payment Arrangement [Member] \| Executive Officer \| Price-Based
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense (credit)		$ 1,300,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period		0
Number of contingently issuable shares		1,000
Class B Common Stock [Member] \| Share-based Payment Arrangement [Member] \| Executive Officer \| Price-Based \| Monte Carlo
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-Based Compensation Arrangement by Share-Based Payment Award, Award other than Options, Grants in Periods, Grante Date Fair Value		$ 3,500,000
Class B Common Stock [Member] \| Share-based Payment Arrangement, Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense (credit)		1,200,000	$ 1,700,000	$ 2,200,000
Total unrecognized compensation expense		$ 4,400,000
Years over which cost expected to be recognized		3 years 8 months 12 days
Options outstanding exercisable now		126,264
Options outstanding exercisable in 2023 (shares)		13,211
Options outstanding exercisable in 2024 (shares)		12,876
Options outstanding exercisable in 2025 (shares)		12,877
Options outstanding exercisable in 2026 (shares)		12,877
Intrinsic value of options outstanding		$ 13,100,000
Intrinsic value of options exercisable		4,000,000
Intrinsic value of options unvested		$ 9,100,000
Options unvested, shares		51,841	65,050
Options unvested, average exercise price (in dollars per share)		$ 429.57	$ 431.16
Options unvested, weighted average remaining contractual term, years		7 years 8 months 12 days	8 years 8 months 12 days
Exercised, Number of Shares		5,084	0	77,258
Intrinsic value of options exercised		$ 1,200,000		$ 11,100,000
Tax benefit from stock option exercises		$ 300,000		$ 2,900,000
Class B Common Stock [Member] \| Subsequent Event [Member] \| Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares awarded	14,630
Class B Common Stock [Member] \| Maximum [Member] \| Share-based Payment Arrangement, Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period		10 years
Class B Common Stock [Member] \| Minimum [Member] \| Share-based Payment Arrangement, Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period		6 years
Class B Common Stock [Member] \| 2012 Incentive Compensation Plan [Member] \| Share-based Payment Arrangement [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved for issuance		206,323
Shares subject to award outstanding		206,323
Class B Common Stock [Member] \| 2022 Incentive Compensation Plan \| Share-based Payment Arrangement [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved for stock awards granted under the plan		500,000
Shares reserved for issuance		499,655
Shares available for future awards		499,655
Class B Common Stock [Member] \| 2022 Incentive Compensation Plan \| Share-based Payment Arrangement [Member] \| non-employee Director
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares awarded		345
Stock-based compensation expense (credit)		$ 200,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period		345
Kaplan Restricted Stock [Member] \| Senior Manager [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares subject to award outstanding		7,206
Kaplan Restricted Stock [Member] \| Subsequent Event [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of company common stock (in dollars per share)	$ 1,565
Exercise Price Above Fair Market Value Of Common Stock [Member] \| Class B Common Stock [Member] \| Share-based Payment Arrangement, Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted		0	0	77,258
Weighted average fair value, granted options (in dollars per share)				$ 93.79