Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Earnings Per Share Reconciliation [Abstract]
Net income attributable to j2 Global, Inc. common shareholders	$ 37,375	$ 28,759	$ 98,169	$ 92,573
Undistributed Earnings (Loss) Allocated to Participating Securities, Basic	611	538	1,620	1,964
Net earnings available to common shareholders	$ 36,764	$ 28,221	$ 96,549	$ 90,609
Weighted-average outstanding shares of common stock - basic	47,696,224	46,845,477	47,553,075	46,653,836
Dilutive effect of equity incentive plans	257,647	318,435	224,547	334,591
Weighted-average outstanding shares of common stock - diluted	47,953,871	47,163,912	47,777,622	46,988,427
Basic	$ 0.77	$ 0.60	$ 2.03	$ 1.94
Diluted	$ 0.77	$ 0.60	$ 2.02	$ 1.93
Share options excluded from the computation of diluted earnings per share	0		62,000	0