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

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- Definition

Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

+ References

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- Definition

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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- Definition

The weighted average fair value at grant date for nonvested equity-based awards issued 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).

+ References

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- Definition

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.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-Paragraph 2
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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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Per share or unit weighted-average fair value of nonvested award under share-based payment arrangement. Excludes share and unit options.

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-Publisher FASB
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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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- Definition

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

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
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-Paragraph 2
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- Definition

The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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Share-Based Compensation - Nonvested Restricted Stock Units (Details) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Restricted Shares
Non-vested, beginning balance (in shares)	3,781,195
Granted (in shares)	1,134,581	928,324	899,269
Vested (in shares)	(899,117)
Forfeited (in shares)	(55,267)
Non-vested, ending balance (in shares)	3,961,392	3,781,195
Weighted- Average Grant- Date Fair Value
Non-vested, beginning balance (usd per share)	$ 26.47
Granted (usd per share	25.98	$ 30.10	$ 28.30
Vested (usd per share)	27.28
Forfeited (usd per share)	24.49
Non-vested, ending balance (usd per share)	$ 26.17	$ 26.47
Class B Common Stock Bonus
Restricted Shares
Granted (in shares)	649,581
Weighted- Average Grant- Date Fair Value
Vesting period, years	3 years
Class B Common Stock Key Employees
Restricted Shares
Granted (in shares)	485,000
Weighted- Average Grant- Date Fair Value
Vesting period, years	10 years