Unrestricted Subsidiaries Unrestricted Subsidiaries (Financial Position) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Cash and cash equivalents	$ 218,680	$ 139,359	$ 64,752	$ 197,411
Accounts Receivable, Net	37,285	19,071
Prepaid expenses and other current assets	15,388	14,311
Deferred income taxes	1,092	1,643
Assets, Current	377,499	212,897
Property and equipment, net	19,599	14,438
Tradenames, net	71,409	34,691
Customer Relationships, Net	64,723	35,865
Goodwill	407,825	279,016	281,848
Other purchased intangibles, net	9,855	9,994
Other assets	3,238	516
Assets	995,170	651,171
Accounts payable and accrued expenses	39,874	24,070
Income taxes payable	3,037	1,510
Deferred revenue	30,493	26,695
Liabilities, Current	78,927	57,798
Deferred income taxes	32,393	12,102
Mandatorily redeemable financial instrument	8,740	0
Liabilities	400,575	96,796
Commitments and contingencies	0	0
Common Stock, Value, Issued	451	554
Additional paid-in capital	169,542	197,374
Retained earnings	424,790	472,595
Accumulated Other Comprehensive Income (Loss), Net of Tax	(88)	(3,477)
Stockholders' equity attributable to j2 Global, Inc.	594,695	554,375	431,745	336,172
Stockholders' Equity Attributable to Noncontrolling Interest	(100)	0	0	0
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	594,595	554,375	431,745	336,172
Liabilities and Equity	995,170	651,171
Ziff Davis, Inc [Member]
Cash and cash equivalents	2,574
Accounts Receivable, Net	16,349
Prepaid expenses and other current assets	494
Deferred income taxes	1,139
Assets, Current	20,556
Property and equipment, net	5,812
Tradenames, net	37,458
Customer Relationships, Net	25,410
Goodwill	112,882
Other purchased intangibles, net	1,216
Other assets	912
Assets	204,246
Accounts payable and accrued expenses	2,372
Income taxes payable	1,374
Deferred revenue	1,973
Liabilities, Current	5,719
Deferred income taxes	21,829
Mandatorily redeemable financial instrument	178,740
Liabilities	206,288
Commitments and contingencies	0
Common Stock, Value, Issued	0
Additional paid-in capital	(2,052)
Retained earnings	(73)
Accumulated Other Comprehensive Income (Loss), Net of Tax	0
Stockholders' equity attributable to j2 Global, Inc.	(2,125)
Stockholders' Equity Attributable to Noncontrolling Interest	83
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	(2,042)
Liabilities and Equity	$ 204,246