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Summary of Significant Accounting Policies - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jun. 30, 2019	Oct. 15, 2018	Feb. 28, 2018	Dec. 31, 2016
Debt Instrument [Line Items]
Unbilled receivables	$ 4,300,000	$ 3,200,000
Allowance for sales credits	(539,000)	(367,000)	$ (226,000)				$ (228,000)
Advertising costs	1,300,000	1,500,000	700,000
Amortization of capitalized software development costs		800,000	500,000
Unrecognized tax benefits	10,738,000	293,000	0
Amount of unrecognized tax benefits reasonably possible to be resolved in next twelve months	$ 10,000,000.0
Conversion price (usd per share)	$ 88.61					$ 57.38
Warrant strike price (usd per share)						$ 78.75
Cloud Lending, Inc.
Debt Instrument [Line Items]
Fair value of contingent earn-out payments					$ 59,500,000
Other Noncurrent Liabilities \| Cloud Lending, Inc.
Debt Instrument [Line Items]
Fair value contingent consideration	$ 24,100,000
Convertible Senior Notes Due February 2023 \| Convertible Debt
Debt Instrument [Line Items]
Principal amount				$ 316,300,000		$ 230,000,000.0
Conversion price (usd per share)	$ 88.61					$ 57.38
Convertible Senior Notes Due June 2026
Debt Instrument [Line Items]
Principal amount				$ 316,300,000
Software Development Costs for Software Sold, Leased or Otherwise Marketed
Debt Instrument [Line Items]
Capitalized software development costs	$ 0	0	1,000,000.0
Amortization of capitalized software development costs	800,000	800,000	500,000
Internal Software Development Costs
Debt Instrument [Line Items]
Capitalized software development costs	200,000	0	0
Amortization of capitalized software development costs	$ 0	$ 0	$ 0