Quarterly Results (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
Quarterly Results [Abstract]
Revenue, Net	$ 138,035	$ 127,788	$ 141,361	$ 113,617	$ 102,033	$ 93,246	$ 89,465	$ 86,652
Gross Profit	115,857	105,987	118,682	93,382	83,375	76,943	73,278	70,788	433,908	304,383	269,546
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
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
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
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