The following table disaggregates the Company’s revenue by geography which provides information as to the major source of revenue (in thousands):

	Three Months Ended September 30,				Nine Months Ended September 30,
Primary Geographic Markets	2019		2018		2019		2018
United States	$	41,827	$	31,140	$	112,483	$	87,318
International		10,720		7,785		31,288		17,948
Total	$	52,547	$	38,925	$	143,771	$	105,266

The following table presents the Company’s revenues disaggregated by revenue source (in thousands):

	Three Months Ended September 30,				Nine Months Ended September 30,
	2019		2018		2019		2018
Subscription services	$	46,385	$	35,998	$	132,043	$	98,327
Professional services		6,162		2,927		11,728		6,939
Total revenues	$	52,547	$	38,925	$	143,771	$	105,266

The Company does not have material amounts of contract assets since revenue is recognized as control of goods is transferred or as services are performed. There are a small number of professional services that may occur over a period of time, but that period of time is generally very short in duration. Any contract assets that may arise are recorded in other assets in the Company’s consolidated balance sheet. As of September 30, 2019, the Company had $1.6 million in receivables related to services performed which were not billed.

The Company’s contract liabilities consist of advance payments and deferred revenue. The Company’s contract liabilities are reported in a net position on a contract-by-contract basis at the end of each reporting period. The Company classifies advance payments and deferred revenue as current or noncurrent based on the timing of when it expects to recognize revenue. Generally, all contract liabilities are expected to be recognized within one year and are included in deferred revenue in the Company’s consolidated balance sheet. The noncurrent portion of deferred revenue is included and separately disclosed in the Company’s consolidated balance sheet.

Current deferred costs, which primarily consist of deferred sales commissions, were $7.7 million and $6.5 million as of September 30, 2019 and December 31, 2018, respectively. Noncurrent deferred costs, which primarily consist of deferred sales commissions, were $12.0 million and $10.3 million as of September 30, 2019 and December 31, 2018, respectively. During the three months ended September 30, 2019 and 2018, amortization expense for the deferred costs was $1.9 million and $1.4 million, respectively. During the nine months ended September 30, 2019 and 2018, amortization expense for the deferred costs was $5.5 million and $3.9 million, respectively. There was no impairment loss in relation to the costs capitalized for the three and nine months ended September 30, 2019 and the year ended December 31, 2018, respectively.

$36.9 million and $77.0 million of subscription services revenue was recognized during the three and nine months ended September 30, 2019 and was included in the deferred revenue balances at the beginning of the respective period. $4.1 million and $5.2 million of professional services revenue was recognized during the three and nine months ended September 30, 2019 and was included in the deferred revenue balances at the beginning of the respective period.

As of September 30, 2019, approximately $250.9 million of revenue is expected to be recognized from remaining performance obligations for subscription contracts.

The Company expects to recognize revenue on approximately $138.8 million of these remaining performance obligations over the next 12 months, with the balance recognized thereafter.

As of September 30, 2019, approximately $12.2 million of revenue is expected to be recognized from remaining performance obligations for professional services contracts. The Company expects to recognize revenue on approximately $8.7 million of these remaining performance obligations over the next 12 months, with the balance recognized thereafter.