Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Earnings Per Share Reconciliation [Abstract]
Net earnings attributable to j2 Global, Inc. common shareholders	$ 20,754	$ 27,806	$ 36,040	$ 22,922	$ 30,203	$ 31,650	$ 31,188	$ 28,539	$ 107,522	$ 121,580	$ 114,766
Net earnings available to participating securities									(2,105)	(2,075)	(1,932)
Net earnings available to common shareholders									$ 105,417	$ 119,505	$ 112,834
Basic	45,867,769	45,729,171	45,428,230	45,160,140	45,071,204	45,002,565	45,373,930	46,400,441	45,548,767	45,459,712	45,799,615
Dilutive effect of equity incentive plans									591,252	321,946	585,233
Diluted	46,382,363	46,291,631	46,018,245	45,668,167	45,423,502	45,340,111	45,569,564	46,794,603	46,140,019	45,781,658	46,384,848
Basic	$ 0.45	$ 0.60	$ 0.78	$ 0.50	$ 0.66	$ 0.69	$ 0.68	$ 0.61	$ 2.31	$ 2.63	$ 2.46
Diluted	$ 0.44	$ 0.59	$ 0.77	$ 0.49	$ 0.65	$ 0.69	$ 0.67	$ 0.60	$ 2.28	$ 2.61	$ 2.43
Share options excluded from the computation of diluted earnings per share									0	527,319	421,319