Fair Value Measurements (Narrative) (Details) (USD $)	3 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2011	Jun. 30, 2011	Dec. 31, 2010
Impairment recognized, related to long-lived assets	$ 300,000	$ 300,000
Short term investments	2,829,000	2,829,000	4,016,000
Estimated fair value of obligation contained in various acquisition agreements		3,500,000	3,300,000
Carrying value of held-to-maturity investments	1,500,000	1,500,000	1,500,000
Fair value of held-to-maturity investments	$ 1,700,000	$ 1,700,000	$ 1,700,000
Base Rate [Member]
Credit risk basis points		1.75
Eurodollar Rate [Member]
Credit risk basis points		2.75