Condensed Consolidating Financials Condensed Statement of Cash Flows (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ 21,877,000	$ 28,765,000
Depreciation and amortization	21,287,000	13,137,000
Accretion (Amortization) of Discounts and Premiums, Investments	273,000	352,000
Amortization of financing costs and discounts	2,222,000	162,000
Share-based Compensation	3,004,000	2,384,000
Excess Tax Benefit from Share-based Compensation, Operating Activities	(334,000)	(4,082,000)
Provision for doubtful accounts	1,610,000	732,000
Deferred income taxes	(494,000)	(211,000)
(Gain) loss on sale of available-for-sale investments	(24,000)	(40,000)
Increase (Decrease) in Accounts Receivable	9,254,000	8,452,000
Increase (Decrease) in Prepaid Expense and Other Assets	(4,000)	(1,657,000)
Increase (Decrease) in Other Operating Assets	25,000	147,000
Accounts payable and accrued expenses	(12,902,000)	(16,228,000)
Income taxes payable	(1,283,000)	4,723,000
Deferred revenue	(1,340,000)	205,000
Liability for uncertain tax positions	2,595,000	351,000
Other	(50,000)	102,000
Net Cash Provided by (Used in) Operating Activities	45,716,000	37,294,000
Maturity of certificates of deposit	0	8,210,000
Sales of available-for-sale investments	28,994,000	29,705,000
Payments to Acquire Available-for-sale Securities	(19,819,000)	(11,213,000)
Payments to Acquire Property, Plant, and Equipment	(2,956,000)	(2,936,000)
Payments to Acquire Businesses, Net of Cash Acquired	(72,215,000)	(49,068,000)
Payments to Acquire Intangible Assets	(327,000)	(915,000)
Payments to Acquire Interest in Subsidiaries and Affiliates	0	0
Net Cash Provided by (Used in) Investing Activities	(66,323,000)	(26,217,000)
Payments for Repurchase of Common Stock	(705,000)	(4,042,000)
Issuance of common stock under employee stock purchase plan	61,000	55,000
Exercise of stock options	65,000	4,926,000
Payments of Dividends	(14,110,000)	(12,418,000)
Excess tax benefits from share-based compensation	334,000	4,082,000
Deferred payments for acquisitions	(2,356,000)	(3,314,000)
Proceeds from (Payments for) Other Financing Activities	(50,000)	0
Payments of Distributions to Affiliates	0	0
Net Cash Provided by (Used in) Financing Activities	(16,761,000)	(10,711,000)
Effect of exchange rate changes on cash and cash equivalents	(4,278,000)	(99,000)
Cash and Cash Equivalents, Period Increase (Decrease)	(41,646,000)	267,000
Cash and cash equivalents	392,017,000	208,068,000
j2 Global, Inc. [Member]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	21,877,000	0
Net Cash Provided by (Used in) Operating Activities	(8,106,000)	0
Maturity of certificates of deposit		0
Sales of available-for-sale investments	21,994,000	0
Payments to Acquire Available-for-sale Securities	(13,276,000)	0
Payments to Acquire Property, Plant, and Equipment	0	0
Payments to Acquire Businesses, Net of Cash Acquired	0	0
Payments to Acquire Intangible Assets	0	0
Payments to Acquire Interest in Subsidiaries and Affiliates	0	0
Net Cash Provided by (Used in) Investing Activities	8,718,000	0
Payments for Repurchase of Common Stock	(705,000)	0
Issuance of common stock under employee stock purchase plan	61,000	0
Exercise of stock options	65,000	0
Payments of Dividends	(14,110,000)	0
Excess tax benefits from share-based compensation	334,000	0
Deferred payments for acquisitions	0	0
Proceeds from (Payments for) Other Financing Activities	0	0
Payments of Distributions to Affiliates	13,232,000	0
Net Cash Provided by (Used in) Financing Activities	(27,587,000)	0
Effect of exchange rate changes on cash and cash equivalents	0	0
Cash and Cash Equivalents, Period Increase (Decrease)	(26,975,000)	0
Cash and cash equivalents	199,815,000	0
j2 Cloud Services, Inc. [Member]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	26,251,000	28,765,000
Net Cash Provided by (Used in) Operating Activities	6,745,000	(3,119,000)
Maturity of certificates of deposit		8,210,000
Sales of available-for-sale investments	7,000,000	24,105,000
Payments to Acquire Available-for-sale Securities	(6,543,000)	(11,213,000)
Payments to Acquire Property, Plant, and Equipment	(308,000)	(454,000)
Payments to Acquire Businesses, Net of Cash Acquired	1,459,000	0
Payments to Acquire Intangible Assets	(5,000)	(591,000)
Payments to Acquire Interest in Subsidiaries and Affiliates	0	(1,021,000)
Net Cash Provided by (Used in) Investing Activities	1,603,000	19,036,000
Payments for Repurchase of Common Stock	0	(4,042,000)
Issuance of common stock under employee stock purchase plan	0	55,000
Exercise of stock options	0	4,926,000
Payments of Dividends	0	(12,418,000)
Excess tax benefits from share-based compensation	0	4,082,000
Deferred payments for acquisitions	(544,000)	0
Proceeds from (Payments for) Other Financing Activities	0	0
Payments of Distributions to Affiliates	27,098,000	(2,335,000)
Net Cash Provided by (Used in) Financing Activities	(27,642,000)	(5,062,000)
Effect of exchange rate changes on cash and cash equivalents	0	0
Cash and Cash Equivalents, Period Increase (Decrease)	(19,294,000)	10,855,000
Cash and cash equivalents	17,516,000	45,261,000
Non-Guarantor Subsidiaries [Member]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	23,539,000	27,942,000
Net Cash Provided by (Used in) Operating Activities	47,077,000	40,413,000
Maturity of certificates of deposit		0
Sales of available-for-sale investments	0	5,600,000
Payments to Acquire Available-for-sale Securities	0	0
Payments to Acquire Property, Plant, and Equipment	(2,648,000)	(2,482,000)
Payments to Acquire Businesses, Net of Cash Acquired	(73,674,000)	(49,068,000)
Payments to Acquire Intangible Assets	(322,000)	(324,000)
Payments to Acquire Interest in Subsidiaries and Affiliates	0	1,021,000
Net Cash Provided by (Used in) Investing Activities	(76,644,000)	(45,253,000)
Payments for Repurchase of Common Stock	0	0
Issuance of common stock under employee stock purchase plan	0	0
Exercise of stock options	0	0
Payments of Dividends	0	0
Excess tax benefits from share-based compensation	0	0
Deferred payments for acquisitions	(1,812,000)	(3,314,000)
Proceeds from (Payments for) Other Financing Activities	(50,000)	0
Payments of Distributions to Affiliates	(40,330,000)	2,335,000
Net Cash Provided by (Used in) Financing Activities	38,468,000	(5,649,000)
Effect of exchange rate changes on cash and cash equivalents	(4,278,000)	(99,000)
Cash and Cash Equivalents, Period Increase (Decrease)	4,623,000	(10,588,000)
Cash and cash equivalents	174,686,000	162,807,000
Consolidation, Eliminations [Member]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	(49,790,000)	(27,942,000)
Net Cash Provided by (Used in) Operating Activities	0	0
Maturity of certificates of deposit		0
Sales of available-for-sale investments	0	0
Payments to Acquire Available-for-sale Securities	0	0
Payments to Acquire Property, Plant, and Equipment	0	0
Payments to Acquire Businesses, Net of Cash Acquired	0	0
Payments to Acquire Intangible Assets	0	0
Payments to Acquire Interest in Subsidiaries and Affiliates	0	0
Net Cash Provided by (Used in) Investing Activities	0	0
Payments for Repurchase of Common Stock	0	0
Issuance of common stock under employee stock purchase plan	0	0
Exercise of stock options	0	0
Payments of Dividends	0	0
Excess tax benefits from share-based compensation	0	0
Deferred payments for acquisitions	0	0
Proceeds from (Payments for) Other Financing Activities	0	0
Payments of Distributions to Affiliates	0	0
Net Cash Provided by (Used in) Financing Activities	0	0
Effect of exchange rate changes on cash and cash equivalents	0	0
Cash and Cash Equivalents, Period Increase (Decrease)	0	0
Cash and cash equivalents	$ 0	$ 0