Investments (Details) (USD $)	3 Months Ended	12 Months Ended
	Sep. 30, 2012	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Investment in Marketable Securities (Textual) [Abstract]
Other comprehensive loss		$ (2,746,000)	$ (4,975,000)	$ (5,000)
Impairment loss	600,000
Short term investments		999,000	20,254,000	0
Marketable securities [Member]
Available-for-sale Securities
Available-for-sale Securities, Amortized Cost		34,786,000	24,819,000
Available-for-sales Securities, Gross Unrealized Losses		(10,443,000)	(4,975,000)
Available-for-sale Securities, Gross Unrealized Gains		2,722,000	0
Available-for-sale Securities, Estimated Fair Value		27,065,000	19,844,000
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Unrealized Losses, Less than twelve months		(2,716,000)
Unrealized Losses, Twelve months or more		(7,727,000)
Unrealized Losses, Total		10,443,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair Value, Less than twelve months		7,728,000
Fair Value, Twelve months or more		4,948,000
Fair Value, Total		$ 12,676,000