Investment In Partnerships (Narrative) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012 item	Dec. 31, 2011	Dec. 31, 2010
Schedule of Equity Method Investments [Line Items]
Final principal installment paid	$ 240
Cash consideration from sale of equity investment	426
Gain on sale of equity investment	822
Hearing Instrument Manufacturers Patent Partnership [Member]
Schedule of Equity Method Investments [Line Items]
Purchase price	1,800
Minority interest purchased	9.00%
Number of patents	45
Acquired finite-lived intangible assets	1,475
Increases (decrease) in carrying amount of investment	(166)	(34)	191
Carrying amount of partnership	773	903
Remaining amount to amortize, 2013	148
Remaining amount to amortize, 2014	148
Remaining amount to amortize, 2015	148
Remaining amount to amortize, 2016	148
Hearing Instrument Manufacturers Patent Partnership [Member] | Patents [Member]
Schedule of Equity Method Investments [Line Items]
Acquired finite-lived intangible assets	345
Acquired finite-lived intangible assets amortization period	10 years
Hearing Instrument Manufacturers Patent Partnership [Member] | Non-Exclusive Patents [Member]
Schedule of Equity Method Investments [Line Items]
Acquired finite-lived intangible assets	1,130
Acquired finite-lived intangible assets amortization period	10 years
Global Coils [Member]
Schedule of Equity Method Investments [Line Items]
Increases (decrease) in carrying amount of investment	50	208	56
Carrying amount of partnership	0	380
Receivable from related party		376
Ownership interest in joint venture	50.00%
Cash consideration from sale of equity investment	426
Gain on sale of equity investment	$ 822