Shareholders Equity - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Stockholders Equity Note [Line Items]
Cash dividends paid per share of Common and Class B common stock	$ 0.70	$ 0.40	$ 1.40	$ 0.80
Shares of non-vested restricted stock granted	19,000	20,000	171,979	203,025
Common stock issued under employee stock purchase plan, shares	2,300	2,181	4,969	4,243
Common stock issued under employee stock purchase plan, net proceeds	$ 275	$ 213	$ 553	$ 403
Class B Common Stock
Stockholders Equity Note [Line Items]
Shares withheld as payment for tax withholdings related to share based compensation, shares	10,133		14,760
Shares withheld as payment for tax withholdings related to share based compensation, market value	$ 1,288		$ 1,837
Carrier Enterprise I
Stockholders Equity Note [Line Items]
Controlling interest, ownership percentage			80.00%
Non-controlling interest, ownership percentage	20.00%		20.00%
Carrier Enterprise II
Stockholders Equity Note [Line Items]
Controlling interest, ownership percentage			60.00%
Non-controlling interest, ownership percentage	40.00%		40.00%
Carrier Enterprise III
Stockholders Equity Note [Line Items]
Controlling interest, ownership percentage			60.00%
Non-controlling interest, ownership percentage	40.00%		40.00%
Common Stock \| Class B Common Stock
Stockholders Equity Note [Line Items]
Stock options exercised, shares	41,000	11,250	66,200	23,500
Stock options exercised, proceeds	$ 1,579	$ 646	$ 2,682	$ 1,329
Common Stock \| Non-Vested (Restricted) Stock
Stockholders Equity Note [Line Items]
Shares withheld as payment for tax withholdings related to share based compensation, shares	7,206	21,028	7,206	21,028
Shares withheld as payment for tax withholdings related to share based compensation, market value	$ 889	$ 2,125	$ 889	$ 2,125
401(k) Plan
Stockholders Equity Note [Line Items]
Common stock contribution to 401(k) Plan, shares			18,343	18,309
Common stock contribution to 401(k) plan			$ 1,963	$ 1,759

Aggregate dividends paid during the period for each share of common stock outstanding.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.3-04)

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The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity.

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Amount of cash outflow to satisfy an employee's income tax withholding obligation as part of a net-share settlement of a share-based award.

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

-Publisher FASB

-Name Accounting Standards Codification

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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.

+ References

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

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For net-share settlement of share-based awards when the employer settles employees' income tax withholding obligations, this element represents the number of shares the employees use to repay the employer.

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Number of shares issued during the period to an employee benefit plan, such as a defined contribution or defined benefit plan.

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Number of shares issued during the period as a result of an employee stock purchase plan.

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Total number of shares issued during the period, including shares forfeited, as a result of Restricted Stock Awards.

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Number of share options (or share units) exercised during the current period.

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

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Value of shares issued during the period to an employee benefit plan, such as a defined contribution or defined benefit plan.

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Aggregate change in value for stock issued during the period as a result of employee stock purchase plan.

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Ownership Percentage

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Stockholders Equity Note [Line Items]

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