Marketable Securities (Narrative) (Details) (USD $)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Gain (Loss) on Investments [Line Items]
Maximum maturity of debt securities, years			3 years
Net pre-tax unrealized gains (losses) for marketable securities	$ (51,000)		$ (51,000)		$ 28,000
Maximum time for loss position, months			12 months		12 months
Proceeds from sale of marketable securities	632,000	952,000	2,936,000	2,800,000
Recognized gain from the sale of marketable securities			6,000
Marketable securities classified as cash equivalents, Recorded basis	2,562,000		2,562,000		685,000
Foreign Accounts [Member]
Gain (Loss) on Investments [Line Items]
Cash	1,978,000		1,978,000		2,296,000
Debt Securities Unrealized Gain Position [Member]
Gain (Loss) on Investments [Line Items]
Fair value	17,208,000		17,208,000		14,207,000
Unrealized gain	46,000		46,000		49,000
Debt Securities Unrealized Loss Position [Member]
Gain (Loss) on Investments [Line Items]
Fair value	4,579,000		4,579,000		2,473,000
Unrealized loss	(50,000)		(50,000)		(3,000)
Marketable Securities - Long-Term [Member]
Gain (Loss) on Investments [Line Items]
Fair value	9,738,000		9,738,000		6,106,000
Unrealized gain	30,000		30,000		37,000
Unrealized loss	(70,000)		(70,000)		(21,000)
Marketable Securities - Long-Term [Member] | Equity Security [Member]
Gain (Loss) on Investments [Line Items]
Fair value	37,000		37,000		66,000
Unrealized loss	$ (47,000)		$ (47,000)		$ (18,000)