Inventory

12 Months Ended

Dec. 31, 2019

Inventory Disclosure [Abstract]

Inventory

6. Inventory

Inventory consisted of the following (in thousands):

	December 31,
	2019		2018
Parts and supplies	$	66,121	$	65,645
Work in progress	8,346		10,688
Inventory	$	74,467	$	76,333

During the years ended December 31, 2019, 2018 and 2017 we recorded write-downs to inventory of $0.9 million, $1.6 million and $2.4 million, respectively, for inventory considered to be excess, obsolete or carried at an amount in excess of net realizable value.