Quarterly report pursuant to Section 13 or 15(d)

Other Assets

Other Assets
9 Months Ended
Sep. 30, 2018
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]  
Other Assets
Other Assets
Other assets consist of the following (in thousands): 
September 30, 2018
December 31, 2017
Costs to obtain contracts


Accumulated amortization of costs to obtain contracts
Unbilled receivables


Operating lease right-of-use assets


Other assets




The Company recorded amortization of costs to obtain contracts of $2.2 million and $1.7 million for the three months ended September 30, 2018 and 2017, respectively, and $6.2 million and $4.7 million for the nine months ended September 30, 2018 and 2017, respectively, in the sales and marketing expense.

The majority of unbilled receivables arise from fixed price escalators included in our long-term Customer Agreements.  The escalator is included in calculating the total estimated transaction value for an individual Customer Agreement.  The average rate is then determined from the transaction value and consistently applied over the term of such Customer Agreement to recognize revenue.  The amount of unbilled receivables increases while the actual billing rate in an individual Customer Agreement is less than the average rate for that Customer Agreement.  Conversely, the amount of unbilled receivables decreases when the actual billing rate escalates and becomes higher than the average rate. At the end of the initial term of a Customer Agreement, the cumulative amounts recognized as revenue and billed to date are the same, therefore the unbilled receivable balance for an individual Customer Agreement will be zero.