Unrestricted Subsidiaries Unrestricted Subsidiaries (Results of Operations) (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
Revenues									$ 599,030	$ 520,801	$ 371,396
Cost of revenues									105,989	86,893	67,013
Gross Profit	138,145	124,974	119,186	110,736	115,857	105,987	118,682	93,382	493,041	433,908	304,383
Selling and Marketing Expense									141,967	131,317	62,825
Research and Development Expense									30,680	25,485	18,624
General and Administrative Expense									134,188	101,683	60,772
Operating Expenses									306,835	258,485	142,221
Operating Income (Loss)									186,206	175,423	162,162
Interest expense (income), net									31,204	21,254	7,650
Other expense (income), net									(165)	11,472	(410)
Income before income taxes									155,167	142,697	154,922
Income tax expense									29,840	35,175	33,259
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
Net Income (Loss) Attributable to Noncontrolling Interest									0	0	83
Net earnings attributable to j2 Global, Inc. common shareholders	31,763	28,759	35,049	28,765	20,754	27,806	36,040	22,922	124,336	107,522	121,580
Ziff Davis, Inc [Member]
Revenues									169,065
Cost of revenues									19,028
Gross Profit									150,037
Selling and Marketing Expense									68,057
Research and Development Expense									5,485
General and Administrative Expense									52,768
Operating Expenses									126,310
Operating Income (Loss)									23,727
Interest expense (income), net									821
Other expense (income), net									347
Income before income taxes									22,559
Income tax expense									4,883
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest									17,676
Net Income (Loss) Attributable to Noncontrolling Interest									0
Net earnings attributable to j2 Global, Inc. common shareholders									$ 17,676