Intangible Assets (Tables)
 12 Months Ended
Dec. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]  
Components of Intangible assets
Amortizing intangible assets consist of the following at December 31:
 
December 31, 2016
 
Cost
 
Accumulated Amortization
 
Net
 
Weighted Average Remaining Life
Raw material supply agreement
$
6,230

 
$
(1,987
)
 
$
4,243

 
9.0 years
Renewable hydrocarbon diesel technology
8,300

 
(1,429
)
 
6,871

 
12.5 years
Acquired customer relationships
2,900

 
(396
)
 
2,504

 
8.6 years
Ground lease
200

 
(127
)
 
73

 
4.9 years
In-process research and development
15,956

 
(177
)
 
15,779

 
14.8 years
Total intangible assets
$
33,586

 
$
(4,116
)
 
$
29,470

 
 
 
December 31, 2015
 
Cost
 
Accumulated Amortization
 
Net
 
Weighted Average Remaining Life
Raw material supply agreement
$
6,230

 
$
(1,551
)
 
$
4,679

 
10.0 years
Renewable hydrocarbon diesel technology
8,300

 
(876
)
 
7,424

 
13.5 years
Acquired customer relationships
2,900

 
(106
)
 
2,794

 
9.6 years
Ground lease
200

 
(112
)
 
88

 
5.9 years
Total amortizing intangibles
17,630

 
(2,645
)
 
14,985

 
 
In-process research and development, indefinite lives
15,956

 
—

 
15,956

 
 
Total intangible assets
$
33,586

 
$
(2,645
)
 
$
30,941

 
 
Estimated amortization expense
Estimated amortization expense for fiscal years ended December 31 is as follows:
2017
$
2,366

2018
2,372

2019
2,379

2020
2,386

2021
2,392

Thereafter
17,575

Total
$
29,470