Business Combinations - Summary of Allocation of Purchase Consideration and Estimated Values of Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands		12 Months Ended
	May 18, 2018	Dec. 31, 2018	Dec. 31, 2017	May 01, 2018	Apr. 03, 2018	Jan. 27, 2017	Dec. 31, 2016
Assets acquired
Goodwill		$ 48,382	$ 31,328				$ 9,676
UMS
Assets acquired
Accounts receivable		3,793
Other assets		2,069
Property and equipment		27
Goodwill		18,278			$ 18,300
Total assets acquired		41,967
Liabilities assumed
Accounts payable and accrued expenses		3,852
Deferred revenue		6,130
Other liabilities		101
Net assets acquired		31,884
Consideration paid
Cash paid, net of cash acquired		31,884
Total		31,884
UMS | Trade Names
Assets acquired
Intangible assets other than goodwill		470
UMS | Acquired Technology
Assets acquired
Intangible assets other than goodwill		930
UMS | Customer Relationships
Assets acquired
Intangible assets other than goodwill		16,400
PlanetRisk, Inc.
Assets acquired
Accounts receivable		2,862
Property and equipment		488
Goodwill		228		$ 200
Total assets acquired		5,988
Liabilities assumed
Accounts payable and accrued expenses		717
Deferred revenue		3,030
Other liabilities		220
Net assets acquired		2,021
Consideration paid
Cash paid, net of cash acquired		2,021
Total		2,021
PlanetRisk, Inc. | Acquired Technology
Assets acquired
Intangible assets other than goodwill		110
PlanetRisk, Inc. | Customer Relationships
Assets acquired
Intangible assets other than goodwill		2,300
Respond B.V.
Assets acquired
Accounts receivable		86
Other assets		87
Property and equipment		19
Goodwill	$ 1,200	1,193
Total assets acquired		3,215
Liabilities assumed
Accounts payable and accrued expenses		226
Deferred revenue		240
Other liabilities		414
Net assets acquired		2,335
Consideration paid
Cash paid, net of cash acquired		1,952
Note payable	400	383
Total	$ 2,300	2,335
Respond B.V. | Trade Names
Assets acquired
Intangible assets other than goodwill		90
Respond B.V. | Acquired Technology
Assets acquired
Intangible assets other than goodwill		140
Respond B.V. | Customer Relationships
Assets acquired
Intangible assets other than goodwill		$ 1,600
IDV Solutions LLC
Assets acquired
Accounts receivable			1,462
Other assets			242
Property and equipment			174
Goodwill			21,196			$ 21,200
Total assets acquired			30,794
Liabilities assumed
Accounts payable and accrued expenses			347
Deferred revenue			4,060
Other liabilities			132
Net assets acquired			26,255
Consideration paid
Cash paid, net of cash acquired			21,235
Note payable			5,020
Total			26,255
IDV Solutions LLC | Trade Names
Assets acquired
Intangible assets other than goodwill			1,590
IDV Solutions LLC | Acquired Technology
Assets acquired
Intangible assets other than goodwill			2,490
IDV Solutions LLC | Customer Relationships
Assets acquired
Intangible assets other than goodwill			3,400
IDV Solutions LLC | Non-compete Arrangement
Assets acquired
Intangible assets other than goodwill			$ 240