No definition available.

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As of the balance sheet date, the projected compensation cost next year of equity-based awards made to employees under equity-based compensation awards that have yet to vest.

+ References

No definition available.

+ Details

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No definition available.

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As of the balance sheet date, the projected compensation cost in fifth fiscal year of equity-based awards made to employees under equity-based compensation awards that have yet to vest.

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No definition available.

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As of the balance sheet date, the projected compensation cost in fourth fiscal year of equity-based awards made to employees under equity-based compensation awards that have yet to vest.

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No definition available.

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As of the balance sheet date, the projected compensation cost in third fiscal year of equity-based awards made to employees under equity-based compensation awards that have yet to vest.

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No definition available.

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As of the balance sheet date, the projected compensation cost in second fiscal year of equity-based awards made to employees under equity-based compensation awards that have yet to vest.

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No definition available.

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Increase (decrease) of stock expense due to waiver of receipt of deferred compensation expense during the period.

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No definition available.

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- Definition

Number of stock award and incentive plan approved by shareholders to provide incentive to key individuals.

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No definition available.

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Number of votes per share entitled to class of shares.

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No definition available.

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Element represents cash payment made during the period.

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No definition available.

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No definition available.

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No definition available.

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Aggregate number of common shares reserved for future issuance.

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-Publisher FASB
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-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.29)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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The per share price that the individual must pay to acquire shares under the deferred compensation arrangement.

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The total fair value of shares issued during the period under a deferred compensation arrangement.

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Number of shares issued pursuant to the terms of a deferred compensation arrangement.

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Unrecognized cost of unvested share-based compensation awards.

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The total recognized tax benefit related to compensation cost for equity-based payment arrangements recognized in income during the period.

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The aggregate amount of noncash, equity-based employee remuneration. This may include the value of stock or unit options, amortization of restricted stock or units, and adjustment for officers' compensation. As noncash, this element is an add back when calculating net cash generated by operating activities using the indirect method.

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Additional share-based compensation cost recognized as a result of an occurrence of an event that accelerates its recognition.

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No definition available.

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Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, 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.

+ References

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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.

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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).

+ References

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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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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

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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.

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No definition available.

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The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units.

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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.

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No definition available.

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

+ References

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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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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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The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

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

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No definition available.

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

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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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.

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No definition available.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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No definition available.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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No definition available.

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated.

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No definition available.

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

+ References

No definition available.

+ Details

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

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No definition available.

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Number of shares for which recognition of compensation cost was accelerated.

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No definition available.

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Percentage of vesting of share-based compensation awards.

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Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

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

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Equity, Voting Rights and Stock Award and Incentive Plan (Details)										3 Months Ended	12 Months Ended
	Sep. 17, 2018 $ / shares shares	Aug. 07, 2018 $ / shares shares	Jul. 02, 2018 USD ($) $ / shares	May 23, 2018 USD ($)	Apr. 04, 2018 $ / shares shares	Jan. 05, 2018 USD ($) shares	Dec. 27, 2017 USD ($) shares	Aug. 07, 2017 USD ($) shares	Jun. 01, 2017 USD ($) shares	Dec. 31, 2017 USD ($) $ / shares shares	Dec. 31, 2018 USD ($) VoteperShare Plan $ / shares shares	Dec. 31, 2017 USD ($) $ / shares shares	Dec. 31, 2016 USD ($) $ / shares shares
Stock Award and Incentive Plan [Abstract]
Number of incentive plans \| Plan											1
Actual and projected stock based compensation expense for RSA shares and options [Abstract]
Compensation cost related to non-vested restricted stock awards and options not yet recognized											$ 8,100,000
Projected compensation cost not yet recognized [Abstract]
2019											2,310,000
2020											2,310,000
2021											1,695,000
2022											1,319,000
2023											499,000
Stock based compensation expense											1,620,000	$ 8,669,000	$ 3,959,000
Tax benefit from compensation expense											$ 400,000	$ 3,300,000	$ 1,500,000
Class A [Member]
Voting Rights [Abstract]
Number of votes per share \| VoteperShare											1
Class A [Member] \| Maximum [Member]
Stock Award and Incentive Plan [Abstract]
Number of shares reserved for issuance under each plan (in shares) \| shares											7,500,000
Class B [Member]
Voting Rights [Abstract]
Number of votes per share \| VoteperShare											10
Stock Options [Member]
Options, shares [Roll Forward]
Outstanding, beginning of period (in shares) \| shares											0	0
Granted (in shares) \| shares											10,000	0
Forfeited (in shares) \| shares											0	0
Exercised / Vested (in shares) \| shares											0	0
Outstanding, end of period (in shares) \| shares										0	10,000	0	0
Shares available for future issuance, end of period (in shares) \| shares											1,087,717
Options, weighted average exercise price [Roll Forward]
Outstanding, beginning of period (in dollars per share) \| $ / shares											$ 0	$ 0
Granted (in dollars per share) \| $ / shares											25.55	0
Forfeited (in dollars per share) \| $ / shares											0	0
Exercised / Vested (in dollars per share) \| $ / shares											0	0
Outstanding, end of period (in dollars per share) \| $ / shares										$ 0	$ 25.55	$ 0	$ 0
Stock Options [Member] \| Maximum [Member]
Stock Award and Incentive Plan [Abstract]
Term of nonqualified stock options											10 years
Stock Options [Member] \| Vesting in Three Years from Date of Grant [Member]
RSAs, weighted average grant date fair value [Abstract]
Award vesting percentage											75.00%
Award vesting period											3 years
Restricted Stock Awards [Member]
RSAs, shares [Roll Forward]
Outstanding, beginning of period (in shares) \| shares											19,400	424,340
Granted (in shares) \| shares	5,000	162,450			270,500						437,950	0
Forfeited (in shares) \| shares											(10,300)	(4,500)
Exercised / Vested (in shares) \| shares											(19,400)	(400,440)
Outstanding, end of period (in shares) \| shares										19,400	427,650	19,400	424,340
RSAs, weighted average grant date fair value [Abstract]
Outstanding, beginning of period (in dollars per share) \| $ / shares											$ 65.67	$ 65.74
Granted (in dollars per share) \| $ / shares	$ 25.74	$ 25.16			$ 24.77						24.93	0
Forfeited (in dollars per share) \| $ / shares											24.81	78.62
Exercised / Vested (in dollars per share) \| $ / shares											65.67	65.60
Outstanding, end of period (in dollars per share) \| $ / shares										$ 65.67	$ 24.93	$ 65.67	$ 65.74
Number of shares with accelerated vesting (in shares) \| shares						19,400	144,650	201,120		144,650	19,400	345,770
Stock compensation expense recognized due to acceleration of lapsing of restrictions on RSAs						$ 200,000	$ 1,300,000	$ 1,800,000		$ 1,300,000	$ 200,000	$ 6,800,000
Restricted Stock Awards [Member] \| Vesting in Three Years from Date of Grant [Member]
RSAs, weighted average grant date fair value [Abstract]
Award vesting percentage											30.00%
Award vesting period											3 years
Restricted Stock Awards [Member] \| Vesting in Five Years from Date of Grant [Member]
RSAs, weighted average grant date fair value [Abstract]
Award vesting percentage											70.00%
Award vesting period											5 years
Restricted Stock Awards [Member] \| Vesting in Year Four from Date of Grant [Member]
RSAs, weighted average grant date fair value [Abstract]
Award vesting percentage											10.00%
Restricted Stock Awards [Member] \| Vesting in Year Five from Date of Grant [Member]
RSAs, weighted average grant date fair value [Abstract]
Award vesting percentage											10.00%
Restricted Stock Awards [Member] \| Vesting in Year Six from Date of Grant [Member]
RSAs, weighted average grant date fair value [Abstract]
Award vesting percentage											10.00%
Restricted Stock Awards [Member] \| Vesting in Year Seven from Date of Grant [Member]
RSAs, weighted average grant date fair value [Abstract]
Award vesting percentage											10.00%
Restricted Stock Awards [Member] \| Vesting in Year Eight from Date of Grant [Member]
RSAs, weighted average grant date fair value [Abstract]
Award vesting percentage											10.00%
Restricted Stock Awards [Member] \| Vesting in Year Nine from Date of Grant [Member]
RSAs, weighted average grant date fair value [Abstract]
Award vesting percentage											10.00%
Restricted Stock Awards [Member] \| Vesting in Year Ten from Date of Grant [Member]
RSAs, weighted average grant date fair value [Abstract]
Award vesting percentage											10.00%
Restricted Stock Awards [Member] \| AC [Member]
RSAs, weighted average grant date fair value [Abstract]
Number of shares with accelerated vesting (in shares) \| shares									420,240
Stock compensation expense recognized due to acceleration of lapsing of restrictions on RSAs									$ 3,700,000
Mr. Gabelli [Member] \| Award Granted for 2016 [Member] \| Vesting on January 1, 2020 [Member]
RSAs, weighted average grant date fair value [Abstract]
Award vesting percentage											100.00%
Mr. Gabelli [Member] \| Award Granted for 2016 [Member] \| Vesting in 2016 [Member]
RSAs, weighted average grant date fair value [Abstract]
Award vesting percentage											25.00%
Mr. Gabelli [Member] \| Award Granted for 2016 [Member] \| Vesting in 2017 [Member]
RSAs, weighted average grant date fair value [Abstract]
Award vesting percentage											25.00%
Mr. Gabelli [Member] \| Award Granted for 2016 [Member] \| Vesting in 2018 [Member]
RSAs, weighted average grant date fair value [Abstract]
Award vesting percentage											25.00%
Mr. Gabelli [Member] \| Award Granted for 2016 [Member] \| Restricted Stock Awards [Member] \| Vesting on January 1, 2020 [Member]
RSAs, weighted average grant date fair value [Abstract]
Award vesting percentage											100.00%
Mr. Gabelli [Member] \| Award Granted for 2016 [Member] \| Restricted Stock Awards [Member] \| Vesting in 2016 [Member]
RSAs, weighted average grant date fair value [Abstract]
Award vesting percentage													25.00%
Deferred compensation agreement, value of shares issued													$ 18,991,316
Mr. Gabelli [Member] \| Award Granted for 2016 [Member] \| Restricted Stock Awards [Member] \| Vesting in 2017 [Member]
RSAs, weighted average grant date fair value [Abstract]
Award vesting percentage												25.00%
Deferred compensation agreement, value of shares issued												$ 18,991,316
Mr. Gabelli [Member] \| Award Granted for 2016 [Member] \| Restricted Stock Awards [Member] \| Vesting in 2018 [Member]
RSAs, weighted average grant date fair value [Abstract]
Award vesting percentage											25.00%
Deferred compensation agreement, value of shares issued											$ 18,991,316
Mr. Gabelli [Member] \| Award Granted for 2016 [Member] \| Restricted Stock Awards [Member] \| Class A [Member]
RSAs, weighted average grant date fair value [Abstract]
Deferred compensation agreement, shares issued (in shares) \| shares													2,314,695
Deferred compensation agreement, share price (in dollars per share) \| $ / shares													$ 32.8187
Deferred compensation agreement, value of shares issued													$ 75,965,266
Closing price (in dollars per share) \| $ / shares										$ 29.65	$ 16.89	$ 29.65	$ 30.89
Reduction of RSU expense due to waiver of receipt of deferred compensation expense											$ (24,000,000)	$ (2,600,000)	$ (1,100,000)
Mr. Gabelli [Member] \| Award Granted for FH 2017 [Member] \| Vesting on July 1, 2018 [Member]
RSAs, weighted average grant date fair value [Abstract]
Award vesting percentage											100.00%
Mr. Gabelli [Member] \| Award Granted for FH 2017 [Member] \| Vesting in 2017 [Member]
RSAs, weighted average grant date fair value [Abstract]
Award vesting percentage											67.00%
Mr. Gabelli [Member] \| Award Granted for FH 2017 [Member] \| Vesting in 2018 [Member]
RSAs, weighted average grant date fair value [Abstract]
Award vesting percentage											33.00%
Mr. Gabelli [Member] \| Award Granted for FH 2017 [Member] \| Restricted Stock Awards [Member] \| Vesting on July 1, 2018 [Member]
RSAs, weighted average grant date fair value [Abstract]
Award vesting percentage											100.00%
Mr. Gabelli [Member] \| Award Granted for FH 2017 [Member] \| Restricted Stock Awards [Member] \| Vesting in 2017 [Member]
RSAs, weighted average grant date fair value [Abstract]
Award vesting percentage											67.00%
Mr. Gabelli [Member] \| Award Granted for FH 2017 [Member] \| Restricted Stock Awards [Member] \| Vesting in 2018 [Member]
RSAs, weighted average grant date fair value [Abstract]
Award vesting percentage											33.00%
Mr. Gabelli [Member] \| Award Granted for FH 2017 [Member] \| Restricted Stock Awards [Member] \| Class A [Member]
RSAs, weighted average grant date fair value [Abstract]
Deferred compensation agreement, shares issued (in shares) \| shares												1,244,018
Deferred compensation agreement, share price (in dollars per share) \| $ / shares												$ 29.6596
Deferred compensation agreement, value of shares issued												$ 36,897,086
Closing price (in dollars per share) \| $ / shares			$ 27.1837							29.65		$ 29.65
Reduction of RSU expense due to waiver of receipt of deferred compensation expense				$ 6,000,000							$ (2,600,000)	$ 17,000
Cash payment amount			$ 28,300,000
Mr. Gabelli [Member] \| Award Granted for Q4 2017 [Member] \| Vesting in 2017 [Member]
RSAs, weighted average grant date fair value [Abstract]
Award vesting percentage											17.00%
Mr. Gabelli [Member] \| Award Granted for Q4 2017 [Member] \| Vesting in 2018 [Member]
RSAs, weighted average grant date fair value [Abstract]
Award vesting percentage											66.00%
Mr. Gabelli [Member] \| Award Granted for Q4 2017 [Member] \| Vesting in April 2019 [Member]
RSAs, weighted average grant date fair value [Abstract]
Award vesting percentage											100.00%
Mr. Gabelli [Member] \| Award Granted for Q4 2017 [Member] \| Restricted Stock Awards [Member] \| Vesting in 2017 [Member]
RSAs, weighted average grant date fair value [Abstract]
Award vesting percentage											17.00%
Mr. Gabelli [Member] \| Award Granted for Q4 2017 [Member] \| Restricted Stock Awards [Member] \| Vesting in 2018 [Member]
RSAs, weighted average grant date fair value [Abstract]
Award vesting percentage											66.00%
Mr. Gabelli [Member] \| Award Granted for Q4 2017 [Member] \| Restricted Stock Awards [Member] \| Vesting in April 2019 [Member]
RSAs, weighted average grant date fair value [Abstract]
Award vesting percentage											100.00%
Mr. Gabelli [Member] \| Award Granted for Q4 2017 [Member] \| Restricted Stock Awards [Member] \| Vesting in 2019 [Member]
RSAs, weighted average grant date fair value [Abstract]
Award vesting percentage											17.00%
Mr. Gabelli [Member] \| Award Granted for Q4 2017 [Member] \| Restricted Stock Awards [Member] \| Class A [Member]
RSAs, weighted average grant date fair value [Abstract]
Deferred compensation agreement, shares issued (in shares) \| shares												530,662
Deferred compensation agreement, share price (in dollars per share) \| $ / shares												$ 29.1875
Deferred compensation agreement, value of shares issued												$ 15,488,708
Closing price (in dollars per share) \| $ / shares										$ 29.65	$ 16.89	$ 29.65
Reduction of RSU expense due to waiver of receipt of deferred compensation expense											$ 5,400,000	$ 0