Note 2. Revenues

Disaggregation of Revenue

We sell our products and services primarily in North America and in selected international markets. Revenue by geography is attributed based on the current billing address of the customer. The following table depicts the disaggregation of revenue by geographic region (in thousands):


	Three Months Ended
	March 31,
	2019		2018
United States
Product sales	$	19,564	$	13,577
Services		5,781		8,423
Total United States		25,345		22,000
Canada
Product sales		16,621		35,698
Services		8,375		11,477
Total Canada		24,996		47,175
Other Countries
Product sales		1,047		833
Services		1,462		678
Total Other Countries		2,509		1,511
Total
Product sales		37,232		50,108
Services		15,618		20,578
Total	$	52,850	$	70,686

Contract Balances

When the timing of the delivery of products and provision of services is different from the timing of the customer payments, we recognize either a contract asset (performance precedes contractual due date in connection with estimates of variable consideration) or a contract liability (customer payment precedes performance) on our condensed consolidated balance sheet. The following table includes the contract assets and liabilities as of March 31, 2019 and January 1, 2019 (in thousands):


	Contract Assets				Contract Liabilities
	Current		Non-Current		Current		Non-Current
Balance at January 1, 2019	$	—	$	—	$	515	$	—
Additions		—		—		68		—
Revenue recognized		—		—		(515)		—
Balance at March 31, 2019	$	—	$	—	$	68	$	—

Our contract liability as of March 31, 2019 and January 1, 2019 is included in current liabilities on our condensed consolidated balance sheet. Our performance obligations for our product and service revenues are usually satisfied before the customer’s payment although prepayments may occasionally be required for international sales. Revenue recognized from the contract liability balance for the three months ended March 31, 2019 was $0.5 million. There was no revenue recognized from the contract liability balance for the three months ended March 31, 2018.

Practical Exemption

We do not disclose the value of unsatisfied performance obligations when the related contract has a duration of one year or less or we recognize revenue equal to what we have the right to invoice when that amount corresponds directly with the value to the customer of our performance to date.