The aggregate number of shares of common stock that may be subject to awards granted in any calendar year.

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The aggregate amount of dividend equivalents charged against retained earnings when dividends were declared.

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- Definition

The percentage Company Match of eligible executive compensation under the Supplemental plan reduced by the amount of any contributions allocated to such executive under the Retirement Plan.

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- Definition

Percentage Of Equity Instruments Other Than Options Vesting Per Year

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Restricted Stock Units Shares Issued Upon Conversion

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- Definition

Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Aggregate Intrinsic Value

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Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested At Specified Date Intrinsic Value

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Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested Number

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- Definition

Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vesting Percentage

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- Definition

Share Based Compensation Arrangement By Share Based Payment Award Vesting Period On Cumulative Basis From Date Of Grant

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Value Of Specified Shares Of Common Stock Equals Each Vested Restricted Stock Unit On Settlement Date

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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.

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- Definition

The amount of payments made for which participants are entitled under a pension plan, including pension benefits, death benefits, and benefits due on termination of employment. Also includes payments made under a postretirement benefit plan, including prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services. This item represents a periodic decrease to the plan obligations and a decrease to plan assets.

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- Definition

Amount of discretionary contributions made by an employer to a defined contribution plan.

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No definition available.

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Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan.

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No definition available.

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Maximum percentage of employee gross pay the employee may contribute to a defined contribution plan.

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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.

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

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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 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 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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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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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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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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

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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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Employee Benefit Plans - Additional Information (Detail) (USD $)	0 Months Ended	12 Months Ended
	May 01, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jan. 05, 2012
Schedule Of Share Based Compensation Arrangements By Share Based Payment Award Options [Line Items]
Grant awards		1,000,000
Maximum number of shares of common stock		100,000
Incentive compensation program vesting percentage	20.00%
Vested of common stock		1
Issuance of common stock		1
Common stock dividends declared		$ 333,000	$ 251,000	$ 82,000
Compensation expense		917,000	971,000	757,000
Employee voluntary contribution		50.00%
Employee compensation		3.00%
Contributions, net of forfeitures		261,000	238,000	270,000
Number of stock option outstanding		5,000	5,000
Stock option exercise price		$ 27.68	$ 27.68
Remaining contractual life		4 years	4 years
Intrinsic value of stock option outstanding		0	0
Restricted Stock Units [Member]
Schedule Of Share Based Compensation Arrangements By Share Based Payment Award Options [Line Items]
Restricted stock awarded		72,125		52,125
RSUs vest starting period from date of grant		1 year
Annual rate of vest of total number of RSUs		20.00%
Compensation expense			962,000
Number of outstanding RSUs		332,525	295,850	216,350	170,825
Restricted Stock Units [Member] \| Employees And Directors [Member]
Schedule Of Share Based Compensation Arrangements By Share Based Payment Award Options [Line Items]
Restricted stock awarded		72,125	79,500	52,125
Termination of grant		10 years
Restricted Stock Units [Member] \| 2012 Incentive Program [Member]
Schedule Of Share Based Compensation Arrangements By Share Based Payment Award Options [Line Items]
Restricted stock awarded			79,500
Unrecognized compensation cost		1,318,000
Restricted Stock Units [Member] \| 2012 Incentive Program [Member] \| Employees And Directors [Member]
Schedule Of Share Based Compensation Arrangements By Share Based Payment Award Options [Line Items]
Restricted stock awarded			35,000
Restricted Stock Units [Member] \| 2004 Omnibus Incentive Compensation Plan [Member]
Schedule Of Share Based Compensation Arrangements By Share Based Payment Award Options [Line Items]
Fair value of grants recognition period		5 years
Compensation expense		910,000		746,000
Weighted average period		3 years 8 months 12 days
Number of outstanding RSUs		332,525
Number of vested RSUs		154,855
Intrinsic value of outstanding RSUs		6,055,000
Intrinsic value of vested RSUs		2,820,000
Restricted Stock Units [Member] \| 2004 Incentive Plan [Member]
Schedule Of Share Based Compensation Arrangements By Share Based Payment Award Options [Line Items]
Unrecognized compensation cost		1,318,000
Supplemental Employee Retirement Plan [Member]
Schedule Of Share Based Compensation Arrangements By Share Based Payment Award Options [Line Items]
Executive compensation		10.00%
Distribution from supplemental plan			0	0
Supplemental Employee Retirement Plan [Member] \| Two Former Officers [Member]
Schedule Of Share Based Compensation Arrangements By Share Based Payment Award Options [Line Items]
Distribution from supplemental plan		$ 2,690,000