Shared-based Compensation (Narrative) (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	$ 3,428	$ 3,081	$ 3,918
Total income tax benefit recognized related to restricted stock awards	230	247	275
Proceeds from stock options exercised	299	44	0
Share-based compensation tax benefit	230	247	275
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	3,400	3,100	3,900
Total income tax benefit recognized related to restricted stock awards	1,200	1,000	1,400
Employee service share based compensation nonvested awards total compensation cost not yet recognized	$ 3,600
Compensation cost recognition weighted average period	1 year 8 months 12 days
Award vesting period	5 years
Shares granted	92,000
Share-based compensation arrangement, fair value of awards vested	$ 3,500	3,900	$ 3,200
Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee service share based compensation nonvested awards total compensation cost not yet recognized	$ 500
Compensation cost recognition weighted average period	1 year 8 months 12 days
Award vesting period	3 years
Share-based compensation, shares authorized under stock option plans, exercise price range, lower range limit	$ 24.26
Share-based compensation arrangement by share-based payment award, options, grants in period, weighted average grant date fair value	7.91
Share-based compensation, shares authorized under stock option plans, exercise price range, upper range limit	$ 31.55
Share based compensation arrangement by share based payment award options expiration term	10 years
Intrinsic value of options exercised	$ 69	$ 10
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee service share based compensation nonvested awards total compensation cost not yet recognized	1,800
Time-Based Restircted Shares [Member] \| Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	$ 800
Share-based compensation arrangement shares to be issued	59,375
Deferred Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	$ 200
Share-based compensation arrangement shares to be issued	210,000
Cost of the award	$ 2,000
Award recognition period end date	Dec. 31, 2019

Share Based Compensation Arrangement By Share Based Payment Award Recognition Period End Date

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- Definition

Expiration term for options outstanding during the reporting period.

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- Definition

Amount of increase in additional paid in capital (APIC) resulting from a tax benefit associated with share-based compensation plan other than an employee stock ownership plan (ESOP). Includes, but is not limited to, excess tax benefit.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
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- Definition

Unrecognized cost of unvested share-based compensation awards.

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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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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 cash inflow associated with the amount received from holders exercising their stock options. This item inherently excludes any excess tax benefit, which the entity may have realized and reported separately.

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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.

+ References

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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

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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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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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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The floor of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range.

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The ceiling of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range.

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Amount of capitalized and expensed compensation cost from equity-based compensation arrangements.

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