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- Definition

Share-based Compensation Arrangement by Share-based Payment Award, Award Measurement Period

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Share-based Compensation Arrangement by Share-based Payment Award, Options, Extensions In Period

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Share-based Compensation Arrangement by Share-based Payment Award, Vesting Price Determining Period

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Share-based Compensation Arrangement by Share-based, Period in Force

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- Definition

Share-base Payment, Performance Period

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- Definition

Share-based Compensation Arrangement by Share-based Payment Award, Performance Factor, Percentage Of Pre-defined Metric Target

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

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Face amount or stated value per share of common stock.

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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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- Definition

Amount of cost to be recognized for option under share-based payment arrangement.

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- Definition

Amount of tax benefit for recognition of expense of award under share-based payment arrangement.

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- Definition

Amount of cash inflow from exercise of option under share-based payment arrangement.

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Estimated period over which an employee is required to provide service in exchange for the equity-based payment award, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

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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Amount of cash paid to settle liability for award under share-based payment arrangement.

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- Definition

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

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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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- Definition

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

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- Definition

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

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- Definition

Price of a single share of a number of saleable stocks of a company.

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Percentage of vesting of award under share-based payment arrangement.

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- Definition

Fair value of options vested. Excludes equity instruments other than options, for example, but not limited to, share units, stock appreciation rights, restricted stock.

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Share-Based Payments (General Descriptions) (Details) - USD ($)		3 Months Ended				9 Months Ended		12 Months Ended
	Jun. 15, 2016	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Jun. 20, 2008
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period in force, from which option holders may elect to sell back acquired shares						90 days
Compensation cost not yet recognized		$ 5,000,000.0				$ 5,000,000.0		$ 11,200,000
Total intrinsic value of options exercised						1,900,000	$ 2,500,000
Total share-based liabilities paid						1,900,000	2,500,000
Fair value of vested awards						1,800,000	3,000,000.0
Cash received from exercise of stock options						$ 0
Shares outstanding (in shares)		0				0		0
Closing stock price (in dollars per share)		$ 182.77				$ 182.77
Pre-tax compensation cost (benefit) recognized		$ (500,000)		$ 1,500,000		$ (4,400,000)	100,000
Compensation cost (benefit), tax expense (benefit)		100,000		$ (300,000)		900,000	$ 0.0
Compensation cost related to nonvested options not yet recognized		$ 2,600,000				$ 2,600,000
Weighted average period over which the compensation is expected to be recognized						1 year 3 months 18 days
Officers and Directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted						0	0
Employee SARs granted before 2016 \| Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Requisite service period of awards (in years)						3 years
Employee Stock Options and SARs \| Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Requisite service period of awards (in years)						1 year
Employee Stock Options and SARs \| Director
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Requisite service period of awards (in years)						1 year
RSU \| Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage (in percentage)						100.00%
Requisite service period of awards (in years)						3 years		3 years
Vesting period (in years)						3 years
RSU \| Director
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Requisite service period of awards (in years)						1 year
PSU
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)						3 years
Performance period (in years)						3 years
Performance outcome period (in years)						3 years
Award measurement period (in years)			3 years		3 years
Performance factor used to determine compensation payout			101.19%		93.86%
Vesting After Service Period, Year One \| Employee SARs granted before 2016 \| Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage (in percentage)						20.00%
Vesting After Service Period, Year One \| Employee SARs \| Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage (in percentage)						33.30%
Vesting After Service Period, Year One \| Employee Stock Options and SARs \| Director
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage (in percentage)						20.00%
Vesting After Service Period, Year Two \| Employee SARs granted before 2016 \| Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage (in percentage)						20.00%
Vesting After Service Period, Year Two \| Employee SARs \| Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage (in percentage)						33.30%
Vesting After Service Period, Year Two \| Employee Stock Options and SARs \| Director
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage (in percentage)						20.00%
Vesting After Service Period, Year Three \| Employee SARs granted before 2016 \| Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage (in percentage)						20.00%
Vesting After Service Period, Year Three \| Employee SARs \| Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage (in percentage)						33.30%
Vesting After Service Period, Year Three \| Employee Stock Options and SARs \| Director
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage (in percentage)						20.00%
Vesting After Service Period, Year Four \| Employee SARs granted before 2016 \| Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage (in percentage)						20.00%
Vesting After Service Period, Year Four \| Employee Stock Options and SARs \| Director
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage (in percentage)						20.00%
Vesting After Service Period, Year Five \| Employee SARs granted before 2016 \| Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage (in percentage)						20.00%
Vesting After Service Period, Year Five \| Employee Stock Options and SARs \| Director
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage (in percentage)						20.00%
2008 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Term of extension	10 years
Class A
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, par value (in dollars per share)		$ 0.01				$ 0.01		$ 0.01
Class A \| RSU \| Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting price determining period						20 days
Class A \| RSU \| Director
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting price determining period						20 days
Class A \| PSU
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting price determining period						20 days
Class A \| 2008 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, par value (in dollars per share)									$ 1.00
Share-based payments, number of shares authorized under plans (in shares)									300,000