Condensed Consolidating Financials Condensed Statement of Cash Flows (Details) (USD $)	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ 63,814,000	$ 58,738,000
Depreciation and amortization	28,455,000	18,241,000
Accretion (Amortization) of Discounts and Premiums, Investments	654,000	820,000
Amortization of financing costs and discounts	641,000	300,000
Share-based Compensation	4,347,000	4,683,000
Excess Tax Benefit from Share-based Compensation, Operating Activities	(4,803,000)	(1,581,000)
Provision for doubtful accounts	1,810,000	1,279,000
Deferred income taxes	(780,000)	(542,000)
(Gain) loss on sale of available-for-sale investments	(40,000)	0
Increase (Decrease) in Accounts Receivable	5,691,000	2,886,000
Increase (Decrease) in Prepaid Expense and Other Assets	(3,151,000)	929,000
Increase (Decrease) in Other Operating Assets	37,000	487,000
Accounts payable and accrued expenses	(3,616,000)	4,998,000
Income taxes payable	(320,000)	212,000
Deferred revenue	364,000	14,049,000
Liability for uncertain tax positions	(1,213,000)	3,512,000
Other	(84,000)	10,000
Net Cash Provided by (Used in) Operating Activities	91,806,000	109,021,000
Maturity of certificates of deposit	14,520,000	31,120,000
Payments to Acquire Other Investments	0	(13,861,000)
Sales of available-for-sale investments	51,929,000	67,261,000
Payments to Acquire Available-for-sale Securities	(45,043,000)	(91,729,000)
Payments to Acquire Property, Plant, and Equipment	(4,631,000)	(5,989,000)
Proceeds from Sale of Productive Assets	608,000	0
Payments to Acquire Businesses, Net of Cash Acquired	(79,546,000)	(81,150,000)
Payments to Acquire Intangible Assets	(3,899,000)	(1,261,000)
Payments to Acquire Interest in Subsidiaries and Affiliates	0	0
Payments for (Proceeds from) Other Investing Activities		0
Net Cash Provided by (Used in) Investing Activities	(66,062,000)	(95,609,000)
Proceeds from Issuance of Long-term Debt	402,500,000	0
Debt issuance costs	(11,069,000)	(47,000)
Payments for Repurchase of Common Stock	(4,733,000)	(2,266,000)
Issuance of common stock under employee stock purchase plan	123,000	106,000
Exercise of stock options	5,247,000	6,524,000
Payments of Dividends	(25,302,000)	(21,762,000)
Excess tax benefits from share-based compensation	4,803,000	1,581,000
PaymentsOfDeferredConsiderationRelatedToAcquisition	13,473,000	0
Proceeds from (Payments for) Other Financing Activities	(217,000)	0
Payments of Distributions to Affiliates	0	0
Net Cash Provided by (Used in) Financing Activities	357,879,000	(15,864,000)
Effect of exchange rate changes on cash and cash equivalents	457,000	(1,302,000)
Cash and Cash Equivalents, Period Increase (Decrease)	384,080,000	(3,754,000)
Cash and cash equivalents	591,881,000	214,926,000
j2 Global, Inc. [Member]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	(671,000)	0
Depreciation and amortization	0	0
Accretion (Amortization) of Discounts and Premiums, Investments	0	0
Amortization of financing costs and discounts	265,000	0
Share-based Compensation	0	0
Excess Tax Benefit from Share-based Compensation, Operating Activities	0	0
Provision for doubtful accounts	0	0
Deferred income taxes	(92,000)	0
(Gain) loss on sale of available-for-sale investments	0
Increase (Decrease) in Accounts Receivable	0	0
Increase (Decrease) in Prepaid Expense and Other Assets	(2,000)	0
Increase (Decrease) in Other Operating Assets	0	0
Accounts payable and accrued expenses	839,000	0
Income taxes payable	(286,000)	0
Deferred revenue	0	0
Liability for uncertain tax positions	0	0
Other	(1,000)	0
Net Cash Provided by (Used in) Operating Activities	52,000	0
Maturity of certificates of deposit	0	0
Payments to Acquire Other Investments	0	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
Proceeds from Sale of Productive Assets	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
Payments for (Proceeds from) Other Investing Activities		0
Net Cash Provided by (Used in) Investing Activities	0	0
Proceeds from Issuance of Long-term Debt	402,500,000
Debt issuance costs	(11,069,000)	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
PaymentsOfDeferredConsiderationRelatedToAcquisition	0
Proceeds from (Payments for) Other Financing Activities	0
Payments of Distributions to Affiliates	0	0
Net Cash Provided by (Used in) Financing Activities	391,431,000	0
Effect of exchange rate changes on cash and cash equivalents	0	0
Cash and Cash Equivalents, Period Increase (Decrease)	391,483,000	0
Cash and cash equivalents	391,483,000	0
j2 Cloud Services, Inc. [Member]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	23,765,000	22,372,000
Depreciation and amortization	3,703,000	4,336,000
Accretion (Amortization) of Discounts and Premiums, Investments	504,000	615,000
Amortization of financing costs and discounts	376,000	301,000
Share-based Compensation	3,850,000	4,683,000
Excess Tax Benefit from Share-based Compensation, Operating Activities	(4,803,000)	(1,581,000)
Provision for doubtful accounts	448,000	711,000
Deferred income taxes	5,000	(556,000)
(Gain) loss on sale of available-for-sale investments	(40,000)
Increase (Decrease) in Accounts Receivable	(789,000)	(983,000)
Increase (Decrease) in Prepaid Expense and Other Assets	(3,845,000)	21,000
Increase (Decrease) in Other Operating Assets	46,000	12,000
Accounts payable and accrued expenses	1,451,000	(2,199,000)
Income taxes payable	(4,849,000)	4,341,000
Deferred revenue	(247,000)	14,962,000
Liability for uncertain tax positions	(1,211,000)	3,512,000
Other	(51,000)	20,000
Net Cash Provided by (Used in) Operating Activities	18,313,000	50,567,000
Maturity of certificates of deposit	8,210,000	22,106,000
Payments to Acquire Other Investments	0	(8,165,000)
Sales of available-for-sale investments	40,340,000	62,261,000
Payments to Acquire Available-for-sale Securities	(45,044,000)	(79,661,000)
Payments to Acquire Property, Plant, and Equipment	(533,000)	(2,482,000)
Proceeds from Sale of Productive Assets	0
Payments to Acquire Businesses, Net of Cash Acquired	55,000	(1,624,000)
Payments to Acquire Intangible Assets	(2,804,000)	(791,000)
Payments to Acquire Interest in Subsidiaries and Affiliates	(1,021,000)	(12,498,000)
Payments for (Proceeds from) Other Investing Activities		3,281,000
Net Cash Provided by (Used in) Investing Activities	(797,000)	(17,573,000)
Proceeds from Issuance of Long-term Debt	0
Debt issuance costs	0	(47,000)
Payments for Repurchase of Common Stock	(4,733,000)	(2,266,000)
Issuance of common stock under employee stock purchase plan	123,000	106,000
Exercise of stock options	5,247,000	6,524,000
Payments of Dividends	(25,302,000)	(21,762,000)
Excess tax benefits from share-based compensation	4,803,000	1,581,000
PaymentsOfDeferredConsiderationRelatedToAcquisition	3,996,000
Proceeds from (Payments for) Other Financing Activities	(54,000)
Payments of Distributions to Affiliates	1,958,000	(62,851,000)
Net Cash Provided by (Used in) Financing Activities	(21,954,000)	(78,715,000)
Effect of exchange rate changes on cash and cash equivalents	0	3,000
Cash and Cash Equivalents, Period Increase (Decrease)	(4,438,000)	(45,718,000)
Cash and cash equivalents	29,968,000	30,994,000
Non-Guarantor Subsidiaries [Member]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	40,720,000	36,366,000
Depreciation and amortization	24,752,000	13,905,000
Accretion (Amortization) of Discounts and Premiums, Investments	150,000	205,000
Amortization of financing costs and discounts	0	(1,000)
Share-based Compensation	497,000	0
Excess Tax Benefit from Share-based Compensation, Operating Activities	0	0
Provision for doubtful accounts	1,362,000	568,000
Deferred income taxes	(693,000)	14,000
(Gain) loss on sale of available-for-sale investments	0
Increase (Decrease) in Accounts Receivable	6,480,000	3,869,000
Increase (Decrease) in Prepaid Expense and Other Assets	696,000	908,000
Increase (Decrease) in Other Operating Assets	(9,000)	475,000
Accounts payable and accrued expenses	(5,906,000)	7,197,000
Income taxes payable	4,815,000	(4,129,000)
Deferred revenue	611,000	(913,000)
Liability for uncertain tax positions	(2,000)	0
Other	(32,000)	(10,000)
Net Cash Provided by (Used in) Operating Activities	73,441,000	58,454,000
Maturity of certificates of deposit	6,310,000	9,014,000
Payments to Acquire Other Investments	0	(5,696,000)
Sales of available-for-sale investments	11,589,000	5,000,000
Payments to Acquire Available-for-sale Securities	1,000	(12,068,000)
Payments to Acquire Property, Plant, and Equipment	(4,098,000)	(3,507,000)
Proceeds from Sale of Productive Assets	608,000
Payments to Acquire Businesses, Net of Cash Acquired	(79,601,000)	(79,526,000)
Payments to Acquire Intangible Assets	(1,095,000)	(470,000)
Payments to Acquire Interest in Subsidiaries and Affiliates	0	0
Payments for (Proceeds from) Other Investing Activities		(3,281,000)
Net Cash Provided by (Used in) Investing Activities	(66,286,000)	(90,534,000)
Proceeds from Issuance of Long-term Debt	0
Debt issuance costs	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
PaymentsOfDeferredConsiderationRelatedToAcquisition	9,477,000
Proceeds from (Payments for) Other Financing Activities	(163,000)
Payments of Distributions to Affiliates	(937,000)	75,349,000
Net Cash Provided by (Used in) Financing Activities	(10,577,000)	75,349,000
Effect of exchange rate changes on cash and cash equivalents	457,000	(1,305,000)
Cash and Cash Equivalents, Period Increase (Decrease)	(2,965,000)	41,964,000
Cash and cash equivalents	170,430,000	183,932,000
Consolidation, Eliminations [Member]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	0	0
Depreciation and amortization	0	0
Accretion (Amortization) of Discounts and Premiums, Investments	0	0
Amortization of financing costs and discounts	0	0
Share-based Compensation	0	0
Excess Tax Benefit from Share-based Compensation, Operating Activities	0	0
Provision for doubtful accounts	0	0
Deferred income taxes	0	0
(Gain) loss on sale of available-for-sale investments	0
Increase (Decrease) in Accounts Receivable	0	0
Increase (Decrease) in Prepaid Expense and Other Assets	0	0
Increase (Decrease) in Other Operating Assets	0	0
Accounts payable and accrued expenses	0	0
Income taxes payable	0	0
Deferred revenue	0	0
Liability for uncertain tax positions	0	0
Other	0	0
Net Cash Provided by (Used in) Operating Activities	0	0
Maturity of certificates of deposit	0	0
Payments to Acquire Other Investments	0	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
Proceeds from Sale of Productive Assets	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	1,021,000	12,498,000
Payments for (Proceeds from) Other Investing Activities		0
Net Cash Provided by (Used in) Investing Activities	1,021,000	12,498,000
Proceeds from Issuance of Long-term Debt	0
Debt issuance costs	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
PaymentsOfDeferredConsiderationRelatedToAcquisition	0
Proceeds from (Payments for) Other Financing Activities	0
Payments of Distributions to Affiliates	(1,021,000)	(12,498,000)
Net Cash Provided by (Used in) Financing Activities	(1,021,000)	(12,498,000)
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