Non-Operating Income and Deductions (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Non-Operating Income and Deductions [Abstract]
Interest income	$ 3,200,000	$ 3,900,000	$ 2,700,000
Interest expense	(3,221,000)	(3,254,000)	(3,336,000)
Foreign exchange gains (losses)	(1,348,000)	(1,211,000)	324,000
Foreign currency translation loss upon liquidation	0	0	0
Foreign currency translation loss upon deconsolidation	0	(1,400,000)	0
Gain on sale of previously impaired assets	0	0	200,000
Gain (loss) on contract termination	0	0	800,000
Other income (deductions)	(1,600,000)	(600,000)	(100,000)
Non-operating income (deductions), net	$ (2,995,000)	$ (2,598,000)	$ 572,000