Inventories

3 Months Ended

Mar. 27, 2020

Inventory Disclosure [Abstract]

Inventories

Inventories

Inventories on the Consolidated Balance Sheets are summarized as follows:

	March 27,		December 31,
(Thousands)	2020		2019
Raw materials and supplies	$	46,843	$	35,612
Work in process	180,123		177,780
Finished goods	26,144		25,506
Subtotal	$	253,110	$	238,898
Less: LIFO reserve balance	48,408		48,508
Inventories	$	204,702	$	190,390

The liquidation of last in, first out (LIFO) inventory layers had no impact to cost of sales in the first quarter of 2020 or 2019.

The Company maintains the majority of the precious metals and copper used in production on a consignment basis in order to reduce our exposure to metal price movements and to reduce our working capital investment. The notional value of off-balance sheet precious metals and copper was $338.5 million as of March 27, 2020 versus $309.3 million as of December 31, 2019.