Patents (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Amortizable intangible assets
Finite-lived intangible assets, gross	$ 6,745	$ 6,745
Finite-Lived intangible assets, accumulated amortization	(5,090)	(4,725)
Finite-lived intangible assets, net	1,655	2,020
Patents Various Group One [Member]
Amortizable intangible assets
Expiration	Various
Estimated useful life of related assets, for patents amortization	5 years
Finite-lived intangible assets, gross	9	9
Patents Various Group Two [Member]
Amortizable intangible assets
Expiration	Various
Estimated useful life of related assets, for patents amortization	7 years
Finite-lived intangible assets, gross	476	476
Patent 5544255 [Member]
Amortizable intangible assets
Expiration	2013
Estimated useful life of related assets, for patents amortization	13 years
Finite-lived intangible assets, gross	93	93
Patent 5647017 [ Member]
Amortizable intangible assets
Expiration	2014
Estimated useful life of related assets, for patents amortization	14 years
Finite-lived intangible assets, gross	187	187
Patent 5818955 [Member]
Amortizable intangible assets
Expiration	2015
Estimated useful life of related assets, for patents amortization	15 years
Finite-lived intangible assets, gross	373	373
Patent 6064751 [Member]
Amortizable intangible assets
Expiration	2017
Estimated useful life of related assets, for patents amortization	17 years
Finite-lived intangible assets, gross	1,213	1,213
Patent 6091835 [Member]
Amortizable intangible assets
Expiration	2017
Estimated useful life of related assets, for patents amortization	17 years
Finite-lived intangible assets, gross	$ 4,394	$ 4,394