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Time vested restricted stock units forfeiture restrictions lapsation percentage.

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No definition available.

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- Definition

Time vested restricted stock units forfeiture restrictions lapsation period.

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No definition available.

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- Definition

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 1

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-Publisher SEC

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- Definition

Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

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- Definition

Unrecognized cost of unvested share-based awards, other than options, awarded to employees as compensation.

+ References

No definition available.

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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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Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

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- Definition

Number of equity instruments other than options outstanding, including both vested and non-vested instruments.

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-Publisher FASB

-Name Accounting Standards Codification

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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).

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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.

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Stock-based Compensation - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Stock Based Compensation [Line Items]
Compensation expense related to incentive plans	$ 4.8	$ 2.4	$ 4.3
Non-Voting Time-Vested Restricted Stock Units [Member]
Stock Based Compensation [Line Items]
Weighted average grant date fair value	$ 43.25	$ 35.09
Aggregate value of vested shares	0.3
Recognized / Unrecognized compensation cost	4.6
Weighted average period	2 years 3 months 4 days
Non-Voting Performance Units [Member]
Stock Based Compensation [Line Items]
Weighted average grant date fair value	$ 43.07
Recognized / Unrecognized compensation cost	5.5
Weighted average period	1 year 9 months 18 days
Maximum [Member] \| Non-Voting Time-Vested Restricted Stock Units [Member]
Stock Based Compensation [Line Items]
Aggregate value of vested shares		$ 0.1
2012 Long - Term Incentive Plan [Member]
Stock Based Compensation [Line Items]
Shares available for issuance	163,676
Forfeiture restrictions percentage	100.00%
Vesting period of employees	3 years
2012 Long - Term Incentive Plan [Member] \| Non-Voting Common Stock [Member]
Stock Based Compensation [Line Items]
Common stock authorized to issue	750,000
1995 Incentive Plan [Member]
Stock Based Compensation [Line Items]
Forfeiture restrictions percentage	100.00%
Vesting period of employees	3 years
1995 Incentive Plan [Member] \| Non-Voting Common Stock [Member]
Stock Based Compensation [Line Items]
Common stock authorized to issue	575,000
Shares available for issuance	738
1995 Incentive Plan [Member] \| Voting Restricted Stock Units [Member]
Stock Based Compensation [Line Items]
Voting common stock outstanding	0	0
1995 Incentive Plan [Member] \| Voting Common Stock [Member]
Stock Based Compensation [Line Items]
Common stock authorized to issue	175,000
Shares available for issuance	32,542