Other Investments (Details 2) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Publicly traded available-for-sale securities
Unrealized loss on marketable securities	$ (15,819,000)	$ 13,116,000	$ (11,137,000)	$ 12,495,000
Total available-for-sale equity securities
Publicly traded available-for-sale securities
Aggregate purchases of publicly traded equity securities classified as available-for-sale	13,800,000		13,800,000
Investment in available-for-sale equity securities			9,300,000
Unrealized loss on marketable securities	(3,000,000)		(3,800,000)
Dividend income on available-for-sale securities	$ 200,000		$ 600,000