Note 11. Segment Information and Foreign Operations

Segment Information

We operate in one segment for the design, development, manufacture and distribution of high-performance compound and single element semiconductor substrates and sale of raw materials integral to these substrates. In accordance with ASC Topic 280, Segment Reporting, our chief operating decision-maker has been identified as our Chief Executive Officer, who reviews operating results to make decisions about allocating resources and assessing performance for the Company. Since we operate in one segment, all financial segment and product line information can be found in the condensed consolidated financial statements.

Product Information

The following table represents revenue amounts (in thousands) by product type:


	Three Months Ended
	March 31,
	2019		2018
Product Type:
Substrates	$	16,766	$	19,364
Raw Materials and Others		3,442		5,055
Total	$	20,208	$	24,419

Geographical Information

The following table represents revenue amounts (in thousands) reported for products shipped to customers in the corresponding geographic region:


	Three Months Ended
	March 31,
	2019		2018
Geographical region:
China	$	7,111	$	7,183
Europe (primarily Germany)		4,375		6,393
Taiwan		3,008		5,049
North America (primarily the United States)		2,738		1,845
Japan		1,792		2,455
Asia Pacific (excluding China, Taiwan and Japan)		1,184		1,494
Total	$	20,208	$	24,419

Long-lived assets consist primarily of property, plant and equipment and operating lease right-of-use assets, and are attributed to the geographic location in which they are located. Long-lived assets, net of depreciation, by geographic region were as follows (in thousands):


	As of
	March 31,		December 31,
	2019		2018
Long-lived assets by geographic region, net of depreciation:
North America	$	1,501	$	445
China		84,510		81,835
	$	86,011	$	82,280

Significant Customers

Two customers, Haisi Optoelectronics and Landmark, represented 12% and 11%, respectively, of our revenue for the three months ended March 31, 2019 while two customers, Landmark and Osram Opto, each represented 12% of our revenue for the three months ended March 31, 2018. Our top five customers, although not the same five customers for each period, represented 40% and 38% of our revenue for the three months ended March 31, 2019 and 2018, respectively.

We perform ongoing credit evaluations of our customers’ financial condition, and limit the amount of credit extended when deemed necessary, but generally do not require collateral. Three customers accounted for 14%, 14% and 12% of our accounts receivable balance as of March 31, 2019, and three customers accounted for 17%, 12% and 10% of our accounts receivable as of December 31, 2018.