Note 11. Deferred Revenue and Performance Obligations

For subscription and services revenue, the Company typically invoices in advance of providing services. Deferred revenue represents the unearned revenue on cash receipts or accounts receivable for the sale of subscriptions and professional services for which services have not yet been provided. In the case where amounts are not collected, but the service has been provided and the revenue has been recognized, the amounts are recorded in accounts receivable. The opening and ending balances of the Company’s deferred revenue are as follows:

	Six Months Ended June 30, 2018
	Subscription			Services			Total
Deferred revenue balance at December 31, 2017	$	110,934		$	8,367		$	119,301
Revenue recognized during the period		(94,677	)		(15,824	)		(110,501	)
Additions to deferred revenue during the period, including deferred revenue acquired		98,095			17,473			115,568
Deferred revenue balance at June 30, 2018	$	114,352		$	10,016		$	124,368

During the three months ended June 30, 2018 and 2017, $44.7 million and $34.5 million of subscription revenue was recognized, respectively, that was included in the deferred revenue balances at the beginning of the respective periods. During the three months ended June 30, 2018 and 2017, $2.4 million and $1.6 million of professional services revenue was recognized, respectively, that was included in the deferred revenue balances at the beginning of the respective periods. During the six months ended June 30, 2018 and 2017, $74.0 million and $61.1 million of subscription revenue was recognized, respectively, that was included in the deferred revenue balances at the beginning of the respective periods. During the six months ended June 30, 2018 and 2017, $5.3 million and $4.4 million of professional services revenue was recognized, respectively, that was included in the deferred revenue balances at the beginning of the respective periods.

Transaction Price Allocated to the Remaining Performance Obligations

As of June 30, 2018, approximately $226.9 million of subscription revenue is expected to be recognized from remaining performance obligations for subscription contracts. The Company expects to recognize revenue on approximately 90% of these remaining performance obligations over the next 24 months, with the balance recognized thereafter. As of June 30, 2018, approximately $12.1 million of services revenue is expected to be recognized from remaining performance obligations for service contracts. The Company will recognize the remaining performance obligations for services revenue as services are performed.