Summary of Significant Accounting Policies - Additional Information (Details)	3 Months Ended		12 Months Ended
	Mar. 31, 2021 USD ($) Customer	Mar. 31, 2020 Customer	Dec. 31, 2019 Customer
Impairment charges | $	$ 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
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]	true
Accounting Standards Update [Extensible List]	evbg:AccountingStandardsUpdate202001Member
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:AccountingStandardsUpdate202001ProspectiveMember
Customer Concentration Risk | Revenue
Number of customers above 10% threshold | Customer	0	0
Customer Concentration Risk | Accounts Receivable
Number of customers above 10% threshold | Customer	0		0
Maximum
Cash and cash equivalent, FDIC insured amount | $	$ 250,000