Shareholders Equity - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Stockholders Equity Note [Line Items]
Cash dividends paid per share of Common and Class B common stock	$ 0.85	$ 0.70	$ 2.55	$ 2.10
Shares of non-vested restricted stock granted	23,803	17,500	135,981	189,479
Common stock issued under employee stock purchase plan, shares	2,084	2,433	6,915	7,402
Common stock issued under employee stock purchase plan, net proceeds	$ 286	$ 294	$ 870	$ 847
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
Stockholders Equity Note [Line Items]
Stock options exercised, proceeds	$ 1,834	$ 999	$ 4,092	$ 3,681
Common Stock | Class B Common Stock
Stockholders Equity Note [Line Items]
Stock options exercised, shares	23,584	14,250	58,084	80,450
Non-Vested Restricted Stock | Common Stock
Stockholders Equity Note [Line Items]
Shares withheld as payment for tax withholdings related to share based compensation, shares	2,936			7,206
Shares withheld as payment for tax withholdings related to share based compensation, market value	$ 419			$ 889
Non-Vested Restricted Stock | Common and Class B Common Stock
Stockholders Equity Note [Line Items]
Shares withheld as payment for tax withholdings related to share based compensation, shares			30,413
Shares withheld as payment for tax withholdings related to share based compensation, market value			$ 3,967
Stock Options | Class B Common Stock
Stockholders Equity Note [Line Items]
Shares withheld as payment for tax withholdings related to share based compensation, shares				14,760
Shares withheld as payment for tax withholdings related to share based compensation, market value				$ 1,837
Stock Options | Common Stock
Stockholders Equity Note [Line Items]
Shares withheld as payment for tax withholdings related to share based compensation, shares	348		348
Shares withheld as payment for tax withholdings related to share based compensation, market value	$ 51		$ 51
401(k) Plan
Stockholders Equity Note [Line Items]
Common stock contribution to 401(k) Plan, shares			20,045	18,343
Common stock contribution to 401(k) plan			$ 2,348	$ 1,963