Description of Business and Summary of Significant Accounting Policies - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2019
Organization Consolidation And Summary Of Significant Accounting Policies [Line Items]
Accounts receivable	$ 87,620	$ 46,023
Depreciation and amortization expense	16,366	14,188	$ 12,358
Capitalized computer software	29,100	11,700	8,300
Total revenue	291,609	249,838	218,876
Prepaid commissions	32,000	13,400
Revenues recognized that were included in the deferred revenue balance	42,400
Advertising costs	28,600	$ 17,400	$ 15,800
Operating lease right of use asset	15,680
Operating lease liability	$ 19,467
Software and software development costs
Organization Consolidation And Summary Of Significant Accounting Policies [Line Items]
Property and equipment, useful life	5 years
Minimum
Organization Consolidation And Summary Of Significant Accounting Policies [Line Items]
Amortization period for prepaid commissions (in years)	3 years
Requisite service period	3 years
Minimum | Computer equipment and software
Organization Consolidation And Summary Of Significant Accounting Policies [Line Items]
Property and equipment, useful life	3 years
Maximum
Organization Consolidation And Summary Of Significant Accounting Policies [Line Items]
Amortization period for prepaid commissions (in years)	5 years
Requisite service period	4 years
Maximum | Computer equipment and software
Organization Consolidation And Summary Of Significant Accounting Policies [Line Items]
Property and equipment, useful life	5 years
ASU No. 2016-02
Organization Consolidation And Summary Of Significant Accounting Policies [Line Items]
Operating lease right of use asset				$ 10,000
Operating lease liability				$ 10,000
Customer Concentration Risk | Accounts Receivable | Two customers
Organization Consolidation And Summary Of Significant Accounting Policies [Line Items]
Accounts receivable	$ 17,600