Business Combinations - Narrative (Details)		12 Months Ended
	Oct. 31, 2017 USD ($)	Dec. 31, 2018 USD ($) company	Dec. 31, 2017 USD ($) company		Dec. 31, 2016 USD ($) company
Business Acquisition [Line Items]
Goodwill		$ 148,845,000	$ 128,728,000	[1]	$ 82,534,000
General and administrative
Business Acquisition [Line Items]
Business acquisition, transaction costs		$ 1,000,000.0	$ 2,400,000		$ 1,000,000.0
2018 Business Combinations
Business Acquisition [Line Items]
Number of business combinations | company		4
Payments to acquire businesses		$ 37,600,000
Net deferred tax liabilities		2,200,000
Goodwill		26,100,000
Goodwill, tax deductible amount		8,000,000.0
2018 Business Combinations | Developed technology
Business Acquisition [Line Items]
Developed technology		$ 13,500,000
Weighted average useful life (in years)		5 years
SkyGiraffe Inc.
Business Acquisition [Line Items]
Payments to acquire businesses	$ 32,300,000
Net deferred tax liabilities	3,341,000
Goodwill	19,386,000
SkyGiraffe Inc. | Developed technology
Business Acquisition [Line Items]
Developed technology	$ 15,600,000
Other 2017 Business Combinations
Business Acquisition [Line Items]
Number of business combinations | company			3
Payments to acquire businesses			$ 26,600,000
Developed technology			9,900,000
Net deferred tax liabilities			3,600,000
Goodwill			20,300,000
Goodwill, tax deductible amount			$ 4,100,000
Other 2017 Business Combinations | Developed technology
Business Acquisition [Line Items]
Weighted average useful life (in years)			5 years
2016 Business Combinations
Business Acquisition [Line Items]
Number of business combinations | company					2
Payments to acquire businesses					$ 34,100,000
Net deferred tax liabilities					4,900,000
Goodwill					26,700,000
Goodwill, tax deductible amount					0
2016 Business Combinations | Developed technology
Business Acquisition [Line Items]
Developed technology					$ 12,800,000
Minimum | 2016 Business Combinations | Developed technology
Business Acquisition [Line Items]
Weighted average useful life (in years)					5 years
Maximum | 2016 Business Combinations | Developed technology
Business Acquisition [Line Items]
Weighted average useful life (in years)					6 years

[1] As adjusted to reflect the impact of the full retrospective adoption of Topic 606.