Property, Plant and Equipment (Tables)
 6 Months Ended
Jun. 30, 2018
Property, Plant and Equipment [Abstract]  
Schedule of Property, Plant and Equipment
The following presents the categories within property, plant and equipment (in thousands):
 
June 30,
 
December 31,
 
2018
 
2017
Operating wind farms
$
4,521,482

 
$
4,640,718

Transmission line
93,849

 
93,849

Furniture, fixtures and equipment
12,285

 
12,643

Land
248

 
141

Subtotal
4,627,864

 
4,747,351

Less: accumulated depreciation
(830,766
)
 
(782,230
)
Property, plant and equipment, net
$
3,797,098

 
$
3,965,121