Document and Entity Information Document - shares	3 Months Ended
	Mar. 31, 2020	May 07, 2020
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2020
Document Transition Report	false
Entity File Number	0-25965
Entity Registrant Name	J2 GLOBAL, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	47-1053457
Entity Address, Address Line One	700 S. Flower Street
Entity Address, Address Line Two	15th Floor
Entity Address, City or Town	Los Angeles
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	90017
City Area Code	323
Local Phone Number	860-9200
Title of 12(b) Security	Common Stock, $0.01 par value
Trading Symbol	JCOM
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		47,713,560
Entity Central Index Key	0001084048
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1
Amendment Flag	false