Summary of Significant Accounting Policies - Additional Information (Details)		12 Months Ended
	Nov. 30, 2020 USD ($)	Dec. 31, 2020 USD ($) Customer	Dec. 31, 2019 USD ($) Customer	Dec. 31, 2018 USD ($) Customer	Jan. 01, 2019 USD ($)
Impairment charges		$ 0
ROU assets		15,045,000	$ 13,071,000
Lease, liability		18,662,000	15,390,000
Short-term investments		0	0
Impairment of goodwill	$ 0	$ 0	0	$ 0
Subscription contracts		The Company’s subscription contracts are generally two years or longer in length, billed annually in advance, and non-cancelable.
Deferred sales commission cost amortization period		4 years
Advertising expenses		$ 4,800,000	$ 1,900,000	$ 1,400,000
Computer and System Software
Property and equipment, useful life in years		3 years
Office Computers
Property and equipment, useful life in years		3 years
Systems Hardware
Property and equipment, useful life in years		5 years
Furniture and Equipment
Property and equipment, useful life in years		5 years
Capitalized Software Development costs
Property and equipment, useful life in years		3 years
Customer Concentration Risk | Revenue
Number of customers above 10% threshold | Customer		0	0	0
Customer Concentration Risk | Accounts Receivable
Number of customers above 10% threshold | Customer		0	0
Minimum
Estimated useful life		1 year
Subscription contracts term		2 years
Minimum | Tradenames
Acquired finite lived intangible assets, useful life		1 year
Minimum | Customer Relationships
Acquired finite lived intangible assets, useful life		5 years
Minimum | Technology
Acquired finite lived intangible assets, useful life		3 years
Maximum
Cash and cash equivalent, FDIC insured amount		$ 250,000
Estimated useful life		9 years
Maximum | Tradenames
Acquired finite lived intangible assets, useful life		7 years
Maximum | Customer Relationships
Acquired finite lived intangible assets, useful life		9 years
Maximum | Technology
Acquired finite lived intangible assets, useful life		4 years
ASU 2016-02
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]			true
Change in Accounting Principle, Accounting Standards Update, Adoption Date			Jan. 01, 2019
Change in Accounting Principle, Accounting Standards Update, Transition Option Elected [Extensible List]			us-gaap:AccountingStandardsUpdate201602RetrospectiveMember
ROU assets					$ 14,700,000
Lease, liability					16,900,000
Deferred rent liability reversed to right-of-use asset upon adoption					$ 2,200,000
ASU 2016-13
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]		true
Change in Accounting Principle, Accounting Standards Update, Adoption Date		Jan. 01, 2020
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false]		true
Change in Accounting Principle, Accounting Standards Update, Transition Option Elected [Extensible List]		evbg:AccountingStandardsUpdates201613RetrospectiveMember
ASU 2018-13
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]		true
Change in Accounting Principle, Accounting Standards Update, Adoption Date		Jan. 01, 2020
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false]		true
Change in Accounting Principle, Accounting Standards Update, Transition Option Elected [Extensible List]		evbg:AccountingStandardsUpdates201813ProspectiveMember
ASU 2018-15
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]		true
Change in Accounting Principle, Accounting Standards Update, Adoption Date		Jan. 01, 2020
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false]		true
Change in Accounting Principle, Accounting Standards Update, Transition Option Elected [Extensible List]		us-gaap:AccountingStandardsUpdate201815ProspectiveMember