Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Intangible assets
Trademarks	$ 40	$ 40
Total intangible assets	7,376	9,931
Less patent amortization	(1,407)	(1,990)
Intangible assets, net	5,969	7,941
Amortization expense	995	688	$ 615
Estimated future aggregate annual amortization expense
2016	580
2017	490
2018	430
2019	397
2020	379
Thereafter	3,653
Total	$ 5,929
Maximum
Intangible assets
Useful life	20 years
Patents | Symyx Asset Purchase Transaction
Intangible assets
Average estimated remaining amortization period	3 years
Patents | Maximum
Intangible assets
Useful life	20 years
Patents issued
Intangible assets
Finite-lived, gross	$ 6,180	6,518
Average estimated amortization period from the date of patents issuance	17 years
Patents pending
Intangible assets
Finite-lived, gross	$ 1,156	$ 3,373