Goodwill and Other Identifiable Intangible Assets (Details) (USD $)	3 Months Ended			3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012	Mar. 31, 2013 Minimum [Member]	Dec. 31, 2012 Minimum [Member]	Mar. 31, 2013 Maximum [Member]	Dec. 31, 2012 Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Patents, accumulated amortization	$ 81,580,000		$ 69,850,000
Useful life of patents and patent rights					1 year		9 years
Weighted average useful life of patents and patent rights	7 years
Patent acquisition costs paid	4,010,000	2,100,000
Finite lived intangible asset acquired during the year, useful life				1 year		10 years
Accelerated amortization expense - up-front payments	$ 483,000	$ 442,000