Property, plant and equipment
 12 Months Ended
Dec. 31, 2013
Property, plant and equipment [Abstract]  
Property, plant and equipment

7. Property, plant and equipment

Property, plant and equipment consist of the following:

 
 
December 31,
 
(in thousands)
 
2013
  
2012
 
Land and improvements
 
$
10,605
  
$
4,839
 
Buildings, building improvements and leasehold improvements
  
83,823
   
66,953
 
Furniture and equipment
  
107,006
   
91,772
 
Software
  
21,832
   
15,691
 
Construction-in-progress
  
98,345
   
105,452
 
 
  
321,611
   
284,707
 
Less: Accumulated depreciation and amortization
  
(57,371
)
  
(42,943
)
Total property, plant and equipment, net
 
$
264,240
  
$
241,764
 

For the years ended December 31, 2013 and 2012, construction-in-progress included costs related to Building 55, the Company's large-scale manufacturing facility, for which the Company is in the process of receiving regulatory approval.

During the year ended December 31, 2013, the Company recorded an impairment related to idle equipment of $1.2 million. The fair value of the asset group was determined via observable prices for similar equipment along with the estimated prices for scrap (salvage value). The impairment is classified in the Company's statements of operations as selling, general and administrative expense with in the Company's Biodefense segment. The impairment reflects management's assessment of the estimated recoverability of the equipment.

Depreciation and amoritization expense was $19.0 million, $11.2 million and $9.4 million for the years ended December 31, 2013, 2012 and 2011, respectively. The increase in depreciation expense as compared to December 31, 2012 was primarily due to the Company's Baltimore facility being placed-in-service in December 2012. As of December 31, 2013, 2012 and 2011 there was no unamortized internal use software-cost.