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- Definition

Fair value of company common stock

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Right To Elect Board Of Directors Percentage

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Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Number Year One

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Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Number Year Three

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Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Number Year Two

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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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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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Number of shares authorized to be repurchased remaining under previous authorization.

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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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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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Capital Stock, Stock Awards, and Stock Options (Narrative) (Details) - USD ($)	1 Months Ended	12 Months Ended
	Jan. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Nov. 09, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Cost of shares repurchased by company		$ 2,103,000	$ 118,030,000	$ 50,770,000
Shares subject to award outstanding		29,140	32,200
Number of shares forfeited due to modification		3,875
Number of shares awarded in 2019		16,802
Exercised, Number of Shares		1,743
Number of shares granted		0
Stock options outstanding		183,189	184,932
Dividends declared per common share		$ 5.56	$ 5.32	$ 5.08
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares excluded from earnings per share			2,650	5,250
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		104,000	104,000	104,000
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		$ (1,300,000)	$ 500,000	$ 1,200,000
Accrual balance related to stock based compensation		10,100,000
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		3,392	199,023	88,361
Cost of shares repurchased by company		$ 2,100,000	$ 118,000,000.0	$ 50,800,000
Number of shares authorized to be repurchased					500,000
Number of shares authorized to be repurchased remaining under previous authorization					163,237
Authorized shares remaining for repurchase		270,263
Market value of company's stock		$ 638.99
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 2020		250
Share awards outstanding, restriction will lapse in 2021		12,975
Share awards outstanding, restriction will lapse in 2023		15,915
Stock-based compensation expense		$ 4,200,000	4,400,000	8,100,000
Total unrecognized compensation expense		$ 9,400,000
Years over which cost expected to be recognized		2 years 1 month 6 days
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		$ 2,000,000.0	$ 2,000,000	$ 2,000,000
Total unrecognized compensation expense		$ 2,300,000
Years over which cost expected to be recognized		1 year 4 months 24 days
Options outstanding exercisable now		160,728
Options outstanding exercisable in 2020		17,334
Options outstanding exercisable in 2021		4,459
Options outstanding exercisable in 2022		333
Options outstanding exercisable in 2023		335
Intrinsic value of options outstanding		$ 25,000,000.0
Intrinsic value of options exercisable		25,000,000.0
Intrinsic value of options unvested		$ 0.0
Options unvested, shares		22,461	39,794
Options unvested, average exercise price		$ 780.81	$ 770.29
Options unvested, weighted average remaining contractual term, years		5 years 4 months 24 days	6 years 3 months 18 days
Exercised, Number of Shares		1,743	588	3,476
Intrinsic value of options exercised		$ 600,000	$ 200,000	$ 700,000
Tax benefit from stock option exercises		$ 200,000	$ 100,000	$ 300,000
Weighted average fair value, granted options				$ 120.47
Class B Common Stock [Member] \| 2003 Employee Stock Option Plan [Member] \| Share-based Payment Arrangement, Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved for stock awards granted under the plan		1,900,000
Shares reserved for issuance		77,258
Class B Common Stock [Member] \| 2003 Employee Stock Option Plan [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] \| 2003 Employee Stock Option Plan [Member] \| Minimum [Member] \| Share-based Payment Arrangement, Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period		4 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 stock awards granted under the plan		772,588
Shares reserved for issuance		559,221
Shares subject to award outstanding		135,071
Shares available for future awards		424,150
Class B Common Stock [Member] \| 2012 Incentive Compensation Plan [Member] \| 2017 Options Granted [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] \| 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] \| 2012 Incentive Compensation Plan [Member] \| Minimum [Member] \| Share-based Payment Arrangement, Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period		6 years
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	$ 1,400
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	2,000