Stockholders' Equity (Details) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Changes in the components of stockholders' equity
Net loss	$ (283,000)	$ 2,371,000
Unrealized gain on available-for-sale securities, net of income tax	6,000	10,000
Repurchase and retirement of common stock	(144,000)	(107,000)
Income tax expense on change in pension net actuarial loss and prior service cost	10,000
Income tax expense on unrealized gain on available-for-sale securities	4,000
Accumulated other comprehensive loss
Net actuarial loss and prior service cost not yet recognized in net periodic benefit cost, net of income tax benefit	(3,250,000)		(3,265,000)
Accumulated unrealized gain on available-for-sale securities, net of income tax expense	23,000		17,000
Accumulated other comprehensive loss	(3,227,000)		(3,248,000)
Income tax benefit of net actuarial loss and prior service cost not yet recognized in net periodic benefit cost	2,175,000		2,185,000
Income tax benefit of accumulated unrealized gain on available-for-sale securities	16,000		12,000
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	19,000
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	1,776,000
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
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	(19,000)
Stock-based compensation	196,000
Repurchase and retirement of common stock	(138,000)
Balance at the end of the period	4,175,000
Retained Earnings
Changes in the components of stockholders' equity
Balance at the beginning of the period	109,322,000
Net loss	(283,000)
Balance at the end of the period	109,039,000
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	15,000
Unrealized gain on available-for-sale securities, net of income tax	6,000
Balance at the end of the period	$ (3,227,000)