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

+ References

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.

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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 seventh 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 sixth fiscal year of equity-based awards made to employees under equity-based compensation awards that have yet to vest.

+ References

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.

+ References

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.

+ References

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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- Definition

Number of shares of common stock issued for each share of common stock the parent company in a spin-off.

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No definition available.

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- Definition

Number of votes per share entitled to class of shares.

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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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-Paragraph 1
-Subparagraph (SX 210.5-02.29)
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No definition available.

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- Definition

Unrecognized cost of unvested options awarded to employees as compensation.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Paragraph 2
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- Definition

Amount of cash outflow for realized tax benefit related to deductible compensation cost reported on the entity's tax return for equity instruments in excess of the compensation cost for those instruments recognized for financial reporting purposes.

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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.

+ References

No definition available.

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- Definition

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 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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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition

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

+ References

No definition available.

+ Details

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- Definition

Percentage of vesting of share-based compensation awards.

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- Definition

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.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Stockholders' Equity, Voting Rights, Stock Award and Incentive Plan (Details) $ / shares in Units, $ in Thousands				3 Months Ended							9 Months Ended		12 Months Ended
	Aug. 07, 2017 shares	Jun. 01, 2017 shares	Nov. 30, 2015 shares	Sep. 30, 2017 USD ($) $ / shares shares	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($) $ / shares shares	Sep. 30, 2016 USD ($) $ / shares shares	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Sep. 30, 2017 USD ($) VoteperShare Plan $ / shares shares	Sep. 30, 2016 USD ($) $ / shares shares	Dec. 31, 2016 USD ($) $ / shares shares
Stock Award and Incentive Plan [Abstract]
Number of incentive plans \| Plan											2
Incremental stock-based compensation expenses due to accelerated vesting				$ 1,800							$ 1,800
Actual and projected stock based compensation expense for RSA shares and options [Abstract]
Actual stock based compensation expense				2,103	$ 4,381	$ 699	$ 691	$ 1,186	$ 1,036	$ 1,037	7,181	$ 3,258	$ 3,950
2017				7,340							7,340
2018				524							524
2019				417							417
2020				246							246
2021				169							169
2022				105							105
2023				48							48
2024				10							10
Employee Service Share-based Compensation, Aggregate Disclosures [Abstract]
Compensation cost related to non-vested options not yet recognized				$ 1,700							$ 1,700
Stock Options [Member] \| Maximum [Member]
Stock Award and Incentive Plan [Abstract]
Term of nonqualified stock options											10 years
Restricted Stock Awards [Member]
Stock Award and Incentive Plan [Abstract]
RSA shares outstanding (in shares) \| shares				164,050			424,340	427,290			164,050	427,290	424,340
Average weighted grant price (in dollars per share) \| $ / shares				$ 66.84			$ 65.74	$ 65.72			$ 66.84	$ 65.72	$ 65.74
Number of shares with accelerated vesting (in shares) \| shares	201,120
Restricted Stock Awards [Member] \| ASU 2016-09 [Member]
Stock Award and Incentive Plan [Abstract]
Tax benefit from stock based compensation expenses				$ (700)							$ (1,000)
Restricted Stock Awards [Member] \| Vesting in Three Years from Date of Grant [Member]
Stock Award and Incentive Plan [Abstract]
Award vesting percentage											30.00%
Award vesting period											3 years
Restricted Stock Awards [Member] \| Vesting in Five Years from Date of Grant [Member]
Stock Award and Incentive Plan [Abstract]
Award vesting percentage											70.00%
Award vesting period											5 years
Restricted Stock Awards [Member] \| Vesting in Year Four from Date of Grant [Member]
Stock Award and Incentive Plan [Abstract]
Award vesting percentage											10.00%
Restricted Stock Awards [Member] \| Vesting in Year Five from Date of Grant [Member]
Stock Award and Incentive Plan [Abstract]
Award vesting percentage											10.00%
Restricted Stock Awards [Member] \| Vesting in Year Six from Date of Grant [Member]
Stock Award and Incentive Plan [Abstract]
Award vesting percentage											10.00%
Restricted Stock Awards [Member] \| Vesting in Year Seven from Date of Grant [Member]
Stock Award and Incentive Plan [Abstract]
Award vesting percentage											10.00%
Restricted Stock Awards [Member] \| Vesting in Year Eight from Date of Grant [Member]
Stock Award and Incentive Plan [Abstract]
Award vesting percentage											10.00%
Restricted Stock Awards [Member] \| Vesting in Year Nine from Date of Grant [Member]
Stock Award and Incentive Plan [Abstract]
Award vesting percentage											10.00%
Restricted Stock Awards [Member] \| Vesting in Year Ten from Date of Grant [Member]
Stock Award and Incentive Plan [Abstract]
Award vesting percentage											10.00%
Restricted Stock Awards [Member] \| AC [Member]
Stock Award and Incentive Plan [Abstract]
Number of shares with accelerated vesting (in shares) \| shares		420,240
Incremental stock-based compensation expenses due to accelerated vesting				0							$ 3,700
Q1 [Member]
Actual and projected stock based compensation expense for RSA shares and options [Abstract]
2018				144							144
2019				113							113
2020				72							72
2021				49							49
2022				32							32
2023				17							17
2024				4							4
Q2 [Member]
Actual and projected stock based compensation expense for RSA shares and options [Abstract]
2018				141							141
2019				113							113
2020				68							68
2021				49							49
2022				32							32
2023				17							17
2024				4							4
Q3 [Member]
Actual and projected stock based compensation expense for RSA shares and options [Abstract]
2018				126							126
2019				101							101
2020				57							57
2021				39							39
2022				24							24
2023				10							10
2024				2							2
Q4 [Member]
Actual and projected stock based compensation expense for RSA shares and options [Abstract]
2017				157							157
2018				113							113
2019				90							90
2020				49							49
2021				32							32
2022				17							17
2023				4							4
2024				$ 0							$ 0
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							7,500,000
Class A [Member] \| Restricted Stock Awards [Member] \| AC [Member]
Stock Award and Incentive Plan [Abstract]
Number of shares of common stock issued for each share of Gamco common stock in spin-off (in shares) \| shares			1
Class B [Member]
Voting Rights [Abstract]
Number of votes per share \| VoteperShare											10