Other Investments (Details 2) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Publicly traded available-for-sale securities
Unrealized gain (loss) on marketable securities	$ (11,248,000)	$ 13,342,000
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
Investment in available-for-sale equity securities	9,300,000
Unrealized gain (loss) on marketable securities	(2,500,000)	900,000
Dividend income on available-for-sale securities	$ 800,000	$ 100,000
Individual securities in continuous unrealized loss position, maximum period (in months)	12