Summary of Significant Accounting Policies - Revenue Recognition and Deferred Costs Narrative (Details)
3 Months Ended
Mar. 31, 2018
USD ($)
Deferred Revenue Arrangement [Line Items]  
Deferred revenue, revenue recognized $ 3,700,000
Deferred costs amortization term 3 years
Deferred contract costs $ 4,300,000
Deferred contract costs, current 1,700,000
Deferred contract costs, noncurrent 2,600,000
Amortization of contract costs 300,000
Capitalized costs impairments $ 0
Core solutions | Minimum  
Deferred Revenue Arrangement [Line Items]  
Subscription agreement term 1 month
Core solutions | Maximum  
Deferred Revenue Arrangement [Line Items]  
Subscription agreement term 1 year