Investments (Narrative) (Details) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2012	Dec. 31, 2011
Investments [Abstract]
Investments, maximum maturity period, years	5	5
Unrealized gains, net of unrealized losses, on the investments in the bond portfolio	$ 1,068,000	$ 786,000