Stockholders' Equity (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Changes in the components of stockholders' equity
Balance at the beginning of the period			$ 113,460,000
Net earnings	223,000	1,147,000	431,000	5,335,000
Unrealized gain on available-for-sale securities, net of income tax	4,000	4,000	7,000	11,000
Repurchase and retirement of common stock			(144,000)	(107,000)
Balance at the end of the period	114,324,000		114,324,000
Income tax expense on change in pension net actuarial loss and prior service cost			30,000
Income tax expense on unrealized gain on available-for-sale securities			5,000
Common Stock | Common stock
Changes in the components of stockholders' equity
Balance at the beginning of the period			1,590,000
Issuance of nonvested stock awards, net of forfeitures			18,000
Conversion of Class A common stock to common stock			173,000
Repurchase and retirement of common stock			(6,000)
Balance at the end of the period	1,775,000		1,775,000
Common Stock | Class A common stock
Changes in the components of stockholders' equity
Balance at the beginning of the period			1,660,000
Conversion of Class A common stock to common stock			(173,000)
Balance at the end of the period	1,487,000		1,487,000
Additional Paid-in Capital
Changes in the components of stockholders' equity
Balance at the beginning of the period			4,136,000
Issuance of nonvested stock awards, net of forfeitures			(18,000)
Stock-based compensation			525,000
Repurchase and retirement of common stock			(138,000)
Balance at the end of the period	4,505,000		4,505,000
Retained Earnings
Changes in the components of stockholders' equity
Balance at the beginning of the period			109,322,000
Net earnings			431,000
Balance at the end of the period	109,753,000		109,753,000
Accumulated Other Comprehensive Loss
Changes in the components of stockholders' equity
Balance at the beginning of the period			(3,248,000)
Change in net actuarial loss and prior service cost, net of income tax expense			45,000
Unrealized gain on available-for-sale securities, net of income tax			7,000
Balance at the end of the period	$ (3,196,000)		$ (3,196,000)