Patents (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Amortizable intangible assets
Finite-lived intangible assets, gross	$ 10,858	$ 10,858
Finite-Lived intangible assets, accumulated amortization	9,112	8,760
Patents [Member]
Amortizable intangible assets
Finite-lived intangible assets, gross	6,746	6,746
Finite-Lived intangible assets, accumulated amortization	5,000	4,726
Capitalized software [Member]
Amortizable intangible assets
Finite-lived intangible assets, gross	4,112	4,112
Finite-Lived intangible assets, accumulated amortization	$ 4,112	$ 4,034