Intangible Assets (Tables)
 12 Months Ended
Dec. 31, 2013
Goodwill and Intangible Assets Disclosure [Abstract]  
Schedule of intangible assets
Intangible assets consist of the following (in thousands):
 
As of
 
As of
 
December 31, 2013
 
December 31, 2012
Patents issued
$
4,893

 
$
3,932

Patents pending
4,224

 
3,386

Trademarks
40

 
40

Total intangible assets
9,157

 
7,358

Less patent amortization
(1,302
)
 
(687
)
Intangible assets, net
$
7,855

 
$
6,671
Finite-lived Intangible Assets Amortization Expense
The following table presents patent amortization expense included in the Consolidated Statement of Operations (in thousands):
 
Years Ended December 31,
 
2013
 
2012
 
2011
Amortization expense
$
615

 
$
588

 
$
81
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense
Estimated future aggregate annual amortization expense for both issued and pending intangible assets is as follows (in thousands):
As of December 31:
 
2014
$
730

2015
699

2016
627

2017
580

2018
500

Thereafter
4,679

Total
$
7,815