Basis Of Presentation (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Revenue	$ 127,788	$ 93,246	$ 382,766	$ 269,363
Net income attributable to j2 Global, Inc. common shareholders	$ 27,806	$ 31,650	$ 86,768	$ 91,377
Basic earnings per share	$ 0.60	$ 0.69	$ 1.88	$ 1.97
Diluted earnings per share	$ 0.59	$ 0.69	$ 1.85	$ 1.96