Consolidated Statements Of Stockholders' Equity Statement (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Stockholders' equity attributable to j2 Global, Inc.	$ 820,235	$ 706,418	$ 820,235	$ 706,418		$ 554,375
Stockholders' Equity Attributable to Noncontrolling Interest	0	0	0	0		0
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	820,235	706,418	820,235	706,418		554,375
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	32,754	20,754	125,327	107,522	121,663
Net earnings attributable to j2 Global, Inc. common shareholders	31,763	20,754	124,336	107,522	121,580
Net Income (Loss) Attributable to Noncontrolling Interest			0	0	83
Comprehensive income attributable to j2 Global, Inc.			113,965	111,845	124,969
Preferred Stock, Accretion of Redemption Discount			0	0	(183)
Stock Repurchased					2,100,000
Preferred Stock Redemption Premium			991	0	0
Additional paid-in capital	273,304	216,872	273,304	216,872
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests				100
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period			(433,008)	(569,204)	(357,234)
Common Stock [Member]
Shares, Outstanding	47,409,514	46,105,076	47,409,514	46,105,076		55,389,636
Stockholders' equity attributable to j2 Global, Inc.	474	461	474	461		554
Stock Issued During Period, Shares, New Issues				234,025
Stock Issued During Period, Value, New Issues				2
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period			433,008	569,204	357,234
Stock Issued During Period, Value, Stock Options Exercised			4	6	4
Stock Issued During Period, Shares, Employee Stock Purchase Plans			5,735	5,402	5,797
Stock Issued During Period, Value, Employee Stock Purchase Plan			0	0	0
Stock Issued During Period, Shares, Restricted Stock Award, Gross			565,713	308,082	204,052
Stock Issued During Period, Value, Restricted Stock Award, Gross			6	3	2
Common Shares Repurchased And Retired During Period Shares			(113,256)	(29,950)	(10,806,648)
Common Shares Repurchased And Retired During Period Value			(1)	0	(108)
Stock Repurchased and Retired During Period, Shares				(75,878)	(55,880)
Stock Repurchased and Retired During Period, Value				(1)	(1)
Series A Preferred Stock [Member]
Stock Issued During Period, Shares, New Issues				5,064
Stock Issued During Period, Value, New Issues				0
Stock Repurchased			(5,064)
Adjustments to Additional Paid in Capital, Other			(4,774)
Additional Paid in Capital, Preferred Stock		4,774		4,774
Series B Preferred Stock [Member]
Stock Issued During Period, Shares, New Issues				4,155
Stock Issued During Period, Value, New Issues				0
Stock Repurchased			(4,155)
Adjustments to Additional Paid in Capital, Other			(6,575)
Additional Paid in Capital, Preferred Stock		6,575		6,575
Additional Paid-in Capital [Member]
Stockholders' equity attributable to j2 Global, Inc.	273,304	216,872	273,304	216,872		197,374
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests				22,900
Stock Issued During Period, Value, Stock Options Exercised			6,617	13,598
Stock Issued During Period, Value, Employee Stock Purchase Plan			265	213
Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt			36,478
Stock Issued During Period, Value, Restricted Stock Award, Gross			(6)	(3)
Common Shares Repurchased And Retired During Period Value			(2,245)	(684)
Stock Repurchased and Retired During Period, Value				(1,506)
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition			8,824	9,585
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation			5,512	3,227
Treasury Stock [Member]
Shares, Outstanding	0	0	0	0		(8,680,568)
Stockholders' equity attributable to j2 Global, Inc.	0	0	0	0		(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.	553,584	484,850	553,584	484,850		472,595
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest			125,327
Net earnings attributable to j2 Global, Inc. common shareholders				107,522	121,580
Dividends, Common Stock, Cash			(52,269)	(45,135)
Preferred Stock Redemption Premium			(991)
Common Shares Repurchased And Retired During Period Value			(3,417)	(2,395)	(129,171)
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition			84	68
Accumulated Other Comprehensive Income (Loss) [Member]
Stockholders' equity attributable to j2 Global, Inc.	(7,127)	4,235	(7,127)	4,235		(3,477)
Comprehensive income attributable to j2 Global, Inc.			(11,362)	4,323	3,389
Extinguishment of Series A Preferred Stock [Member]
Stock Issued During Period, Shares, New Issues			235,665
Stock Issued During Period, Value, New Issues			2
Exchange of Series B Preferred Stock [Member]
Stock Issued During Period, Shares, New Issues			177,573
Stock Issued During Period, Value, New Issues			$ 2