5.	Inventories

Inventories consist primarily of telecommunications systems and parts, and are recorded at the lower of cost (average cost) or market. We evaluate the need for write-downs associated with obsolete, slow-moving, and nonsalable inventory by reviewing net realizable inventory values on a periodic basis.

Inventories as of March 31, 2018 and December 31, 2017 were as follows (in thousands):


	March 31,		December 31,
	2018		2017
Work-in-process component parts	$	32,458	$	35,009
Finished goods (1)		136,324		10,534

Total inventory	$	168,782	$	45,543

(1)

The increase in our inventories is primarily due to the allocation of a portion of our uninstalled airborne equipment (i.e., shipsets designated for installation under an airline-directed contract) within our CA-NA and CA-ROW segments from property and equipment, net, to inventories. Historically, all uninstalled airborne equipment for the CA-NA and CA-ROW segments was classified as property and equipment, net, as the majority of our installations were performed under our turnkey model agreements. See Note 11, “Leases” for additional information on the turnkey model treatment. As our uninstalled airborne equipment is increasingly being deployed under airline-directed model agreements, we now allocate our uninstalled airborne equipment between property and equipment, net, and inventories, based on our forecasts of estimated future installations by contract type.