Consolidated Statements Of Stockholders' Equity Statement (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Stockholders' equity attributable to j2 Global, Inc.	$ 594,695	$ 594,695	$ 554,375	$ 431,745	$ 336,172
Stockholders' Equity Attributable to Noncontrolling Interest	(100)	(100)	0	0	0
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	594,595	594,595	554,375	431,745	336,172
Net earnings attributable to j2 Global, Inc. common shareholders	30,203	121,580	114,766	83,047
Net Income (Loss) Attributable to Noncontrolling Interest		83	0	0
Comprehensive income attributable to j2 Global, Inc.		124,969	113,324	81,987
Preferred Stock, Accretion of Redemption Discount		(183)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period		(357,234)	(1,820,678)	(816,552)
Common Stock [Member]
Shares, Outstanding	45,094,191	45,094,191	55,389,636	53,700,629	52,907,691
Stockholders' equity attributable to j2 Global, Inc.	451	451	554	537	529
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period		357,234	1,820,678	816,552
Stock Issued During Period, Value, Stock Options Exercised		4	18	8
Stock Issued During Period, Shares, Employee Stock Purchase Plans		5,797	5,235	4,894
Stock Issued During Period, Value, Employee Stock Purchase Plan		0	0	1
Stock Issued During Period, Shares, Restricted Stock Award, Gross		204,052	155,024	190,683
Stock Issued During Period, Value, Restricted Stock Award, Gross		2	1	2
Common Shares Repurchased And Retired During Period Shares		(10,806,648)	(248,152)	(165,604)
Common Shares Repurchased And Retired During Period Value		(108)	(2)	(2)
Stock Repurchased and Retired During Period, Shares		(55,880)	(43,778)	(53,587)
Stock Repurchased and Retired During Period, Value		(1)	0	(1)
Additional Paid-in Capital [Member]
Stockholders' equity attributable to j2 Global, Inc.	169,542	169,542	197,374	164,769	147,619
Stock Issued During Period, Value, Stock Options Exercised		5,642	14,404	7,488
Stock Issued During Period, Value, Employee Stock Purchase Plan		157	142	108
Stock Issued During Period, Value, Restricted Stock Award, Gross		(2)	(1)	(2)
Common Shares Repurchased And Retired During Period Value		(42,580)	(3,616)	(344)
Stock Repurchased and Retired During Period, Value		(1,093)	(853)	(1,099)
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition		9,083	8,968	10,937
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation		961	13,561	62
Treasury Stock [Member]
Shares, Outstanding	0	0	(8,680,568)	(8,680,568)	(8,680,568)
Stockholders' equity attributable to j2 Global, Inc.	0	0	(112,671)	(112,671)	(112,671)
Common Shares Repurchased And Retired During Period Shares		8,680,568
Common Shares Repurchased And Retired During Period Value		112,671
Retained Earnings [Member]
Stockholders' equity attributable to j2 Global, Inc.	424,790	424,790	472,595	381,145	301,670
Net earnings attributable to j2 Global, Inc. common shareholders		121,580	114,766	83,047
Dividends, Common Stock, Cash		(40,263)	(19,199)
Common Shares Repurchased And Retired During Period Value		(129,171)	(4,142)	(3,572)
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition		49	25
Accumulated Other Comprehensive Income (Loss) [Member]
Stockholders' equity attributable to j2 Global, Inc.	(88)	(88)	(3,477)	(2,035)	(975)
Comprehensive income attributable to j2 Global, Inc.		$ 3,389	$ (1,442)	$ (1,060)