Deferred Costs	9 Months Ended
Sep. 30, 2018
Deferred Costs Capitalized Prepaid And Other Assets Disclosure [Abstract]
Deferred Costs	Note 4. Deferred costs Deferred costs, which primarily consist of deferred sales commissions, were $33.0 million and $29.1 million as of September 30, 2018 and December 31, 2017, respectively. The Company capitalized $5.4 million and $4.5 million during the three months ended September 30, 2018 and 2017, respectively, and $13.6 million and $10.6 million during the nine months ended September 30, 2018 and 2017, respectively. In addition, the Company acquired $2.7 million of deferred costs related to capitalized commissions and reseller fees, in connection with the business combination noted below. Amortization expense for the deferred costs was $4.3 million and $3.5 million during the three months ended September 30, 2018 and 2017, respectively, and $12.2 million and $10.1 million during the nine months ended September 30, 2018 and 2017, respectively. Impairment losses related to deferred costs were immaterial for the three and nine months ended September 30, 2018.

Note 4. Deferred costs

Deferred costs, which primarily consist of deferred sales commissions, were $33.0 million and $29.1 million as of September 30, 2018 and December 31, 2017, respectively. The Company capitalized $5.4 million and $4.5 million during the three months ended September 30, 2018 and 2017, respectively, and $13.6 million and $10.6 million during the nine months ended September 30, 2018 and 2017, respectively. In addition, the Company acquired $2.7 million of deferred costs related to capitalized commissions and reseller fees, in connection with the business combination noted below. Amortization expense for the deferred costs was $4.3 million and $3.5 million during the three months ended September 30, 2018 and 2017, respectively, and $12.2 million and $10.1 million during the nine months ended September 30, 2018 and 2017, respectively. Impairment losses related to deferred costs were immaterial for the three and nine months ended September 30, 2018.