Share based award option expiration period from grant date.

No definition available.

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- Definition

Share based compensation arrangement by share based payment award maximum additional number of shares shares authorized description.

+ References

No definition available.

+ Details

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- Definition

Share based compensation arrangement by share based payment award maximum additional number of shares shares authorized percentage.

+ References

No definition available.

+ Details

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (l)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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- Definition

Unrecognized cost of unvested share-based compensation awards.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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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.

+ References

No definition available.

+ Details

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- Definition

Number of additional shares authorized for issuance under an established share-based compensation plan.

+ References

No definition available.

+ Details

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- Definition

The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

+ Details

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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

+ Details

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- Definition

Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (e)(1)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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- Definition

The number of shares authorized to be repurchased by an entity's Board of Directors under a stock repurchase plan.

+ References

No definition available.

+ Details

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Period Type:	instant

- Definition

The remaining number of shares authorized to be repurchased by an entity's Board of Directors under a stock repurchase plan.

+ References

No definition available.

+ Details

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- Details

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Restricted Stock, Stock Options and Other Stock Plans - Additional Information (Detail) - USD ($) $ in Millions		12 Months Ended
	Dec. 14, 2004	Dec. 31, 2017	Dec. 31, 2016	Nov. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average remaining contractual term of unexercised stock options		8 years 6 months	4 years 9 months 18 days
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted by the company			0
Class A [Member] \| November 2014 New Share Repurchase Program [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Remaining common stock available for repurchase under share repurchase program		404,000	404,000
2004 Long-Term Compensation Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Long-term compensation plan stock option expiration period	10 years
Unrecognized compensation cost related to stock issuances		$ 0.6	$ 0.1
2004 Long-Term Compensation Plan [Member] \| Class A [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Authorized increase in number of shares		1,000,000
Shares issued		107
Description of additional shares authorized for issuance under long-term compensation plan		The Plan provided an initial authorization of 0.4 million shares of Class A common stock for issuance and allows an automatic annual increase equal to the lesser of (i) 3% of the Class A common stock outstanding (ii) 107 shares or (iii) such lesser amount as may be determined by the Company’s board of directors.
Shares available for issuance under long-term compensation plan		400,000	300,000
Percentage of additional shares authorized issuable under long-term compensation plan		3.00%
Minimum [Member] \| 2004 Long-Term Compensation Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Long-term compensation plan vesting period	1 year
Maximum [Member] \| Class A [Member] \| November 2014 New Share Repurchase Program [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
New share repurchase program, shares authorized to repurchase				429,000
Maximum [Member] \| 2004 Long-Term Compensation Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Long-term compensation plan vesting period	5 years