Condensed Consolidated Statements of Shareholders' Equity (Unaudited) (USD $) In Thousands	Total	Voting Common Stock	Non-Voting Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings
Balance at Dec. 31, 2009	$ 465,448	$ 285	$ 1,246	$ 291,403	$ (13)	$ 172,527
Balance, shares at Dec. 31, 2009		2,853	12,459
Net earnings (loss)	11,085					11,085
Changes in pension plan assets and benefit obligations	(13)				(13)
Total comprehensive income, net of income taxes	11,072
Balance at Jun. 30, 2010	476,520	285	1,246	291,403	(26)	183,612
Balance, shares at Jun. 30, 2010		2,853	12,459
Balance at Dec. 31, 2010	472,416	285	1,246	291,403	(162)	179,644
Balance, shares at Dec. 31, 2010		2,853	12,459
Net earnings (loss)	(1,948)					(1,948)
Unrealized gain on short-term investments	151				151
Changes in pension plan assets and benefit obligations	1				1
Total comprehensive income, net of income taxes	(1,796)
Balance at Jun. 30, 2011	$ 470,620	$ 285	$ 1,246	$ 291,403	$ (10)	$ 177,696
Balance, shares at Jun. 30, 2011		2,853	12,459