Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Earnings Per Share Reconciliation [Abstract]
Net income attributable to j2 Global, Inc. common shareholders	$ 27,806	$ 31,650	$ 86,768	$ 91,377
Net earnings available to participating securities	(416)	(513)	(1,455)	(1,512)
Net earnings available to common shareholders	$ 27,390	$ 31,137	$ 85,313	$ 89,865
Weighted-average outstanding shares of common stock - basic	45,729,171	45,002,565	45,441,265	45,590,160
Dilutive effect of equity incentive plans	562,460	337,546	625,339	307,229
Weighted-average outstanding shares of common stock - diluted	46,291,631	45,340,111	46,066,604	45,897,389
Basic	$ 0.60	$ 0.69	$ 1.88	$ 1.97
Diluted	$ 0.59	$ 0.69	$ 1.85	$ 1.96
Share options excluded from the computation of diluted earnings per share	0	420,319	0	536,559