Stockholder Rights Plan (Details Textual)	12 Months Ended
	Dec. 31, 2011	Dec. 05, 2008
Stockholder Rights Plan (Textual Abstract)
Minimum percentage of ownership of outstanding voting stock give right to purchase common stock at half the market price		15.00%
Berkshire Hathaway shareholder's agreement Standstill period	7 years
Minimum percentage of voting stock acquired by Berkshire Hathaway and its affiliates on fully diluted basis	50.00%
Limit on Berkshire Hathaway acquisitions of beneficial ownership of our voting stock	40.00%
Period of review rights plan	3 years