Condensed Consolidating Financials Condensed Consolidating Comprehensive Income Statement (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ 32,754	$ 28,759	$ 35,049	$ 28,765	$ 20,754	$ 27,806	$ 36,040	$ 22,922	$ 125,327	$ 107,522	$ 121,663
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax									(14,694)	78	1,435
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax									3,332	4,245	1,954
Other Comprehensive Income (Loss), Net of Tax									(11,362)	4,323	3,389
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest									113,965	111,845	125,052
Net Income (Loss) Attributable to Noncontrolling Interest									0	0	83
Comprehensive income attributable to j2 Global, Inc.									113,965	111,845	124,969
j2 Global, Inc. [Member]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest									125,327	0	0
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax									0	0	0
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax									15	0	0
Other Comprehensive Income (Loss), Net of Tax									15	0	0
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest									125,342	0	0
Net Income (Loss) Attributable to Noncontrolling Interest									0	0	0
Comprehensive income attributable to j2 Global, Inc.									125,342	0	0
j2 Cloud Services, Inc. [Member]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest									135,838	107,522	121,580
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax									(478)	(43)	521
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax									3,307	4,249	1,960
Other Comprehensive Income (Loss), Net of Tax									2,829	4,206	2,481
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest									138,667	111,728	124,061
Net Income (Loss) Attributable to Noncontrolling Interest									0	0	0
Comprehensive income attributable to j2 Global, Inc.									138,667	111,728	124,061
Non-Guarantor Subsidiaries [Member]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest									77,051	61,551	91,622
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax									(14,216)	121	914
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax									10	(4)	(6)
Other Comprehensive Income (Loss), Net of Tax									(14,206)	117	908
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest									62,845	61,668	92,530
Net Income (Loss) Attributable to Noncontrolling Interest									0	0	83
Comprehensive income attributable to j2 Global, Inc.									62,845	61,668	92,447
Consolidation, Eliminations [Member]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest									(212,889)	(61,551)	(91,539)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax									0	0	0
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax									0	0	0
Other Comprehensive Income (Loss), Net of Tax									0	0	0
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest									(212,889)	(61,551)	(91,539)
Net Income (Loss) Attributable to Noncontrolling Interest									0	0	0
Comprehensive income attributable to j2 Global, Inc.									$ (212,889)	$ (61,551)	$ (91,539)