Revenue

The Company differentiates revenue and cost of revenue (excluding depreciation and amortization) based on whether the source of revenue is attributable to products or services. Revenue and cost of revenue (excluding depreciation and amortization) by source are as follows (in thousands):



	Year ended December 31,
	2017		2016		2015
Revenue:
Products	$	310,716	$	256,263	$	258,968
Services	6,382		6,569		10,998
	$	317,098	$	262,832	$	269,966
Cost of revenue (excluding depreciation and amortization):
Products	$	210,281	$	162,488	$	164,837
Services	4,848		7,767		7,196
	$	215,129	$	170,255	$	172,033