Inventories

3 Months Ended

Mar. 31, 2019

Inventory Disclosure [Abstract]

Inventories

13. Inventories

Costs included in inventories are raw materials, labor, supplies and allocable depreciation and overhead. Raw material inventories are valued on an average cost basis. Other inventory cost elements are valued at cost, using the first-in, first-out method. The Company writes down the inventories for estimated obsolescence, and to lower of cost or net realizable value based upon assumptions about future demand and market conditions. If actual demand or market conditions are less favorable than those projected by the Company, additional inventory write-downs may be required. Once established, the original cost of the inventory less the related write-down represents the new cost basis of such inventories.

As of March 31, 2019 and December 31, 2018, Inventories consisted of the following:

(in thousands)	March 31, 2019	December 31, 2018
Raw materials	$47,820	$40,489
Work in process	37,582	33,181
Finished goods	16,977	12,234
Total inventories	$102,379	$85,904