Inventories (Tables)
3 Months Ended
Mar. 31, 2020
Inventory Disclosure [Abstract]  
Summary of Significant Components of Inventory

Inventories are valued at the lower of cost (using specific identification and first-in first-out methods) or net realizable value. The significant components of inventory were as follows:

 

(in thousands)

 

March 31, 2020

 

 

December 31, 2019

 

Raw materials

 

$

103,840

 

 

$

102,438

 

Installations in process

 

 

3,055

 

 

 

2,303

 

 

 

$

106,895

 

 

$

104,741