5. Inventories



	March 31,		December 31,
	2018		2017
	(Dollars in thousands)
Raw materials	$	121,840	$	112,300
Work in process		54,626		39,454
Finished goods		181,617		172,426
Total inventories	$	358,083	$	324,180

In the production of some of our products, we use precious metals, which we obtain from financial institutions under consignment agreements with terms of one year or less. The financial institutions retain ownership of the precious metals and charge us fees based on the amounts we consign. These fees were $0.4 million and $0.2 million for the three months ended March 31, 2018 and 2017, respectively. We had on-hand precious metals owned by participants in our precious metals consignment program of $39.6 million at March 31, 2018, and $37.7 million at December 31, 2017, measured at fair value based on market prices for identical assets.