Condensed Consolidating Financials Condensed Statement of Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015	Dec. 31, 2014
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ 29,943	$ 21,877
Depreciation and amortization	27,174	21,287
Accretion (Amortization) of Discounts and Premiums, Investments	331	273
Amortization of financing costs and discounts	2,370	2,222
Share-based Compensation	2,809	3,004
Excess Tax Benefit from Share-based Compensation, Operating Activities	(264)	(334)
Provision for doubtful accounts	2,825	1,610
Deferred income taxes	(3,101)	(494)
(Gain) loss on sale of available-for-sale investments	(182)	24
Decrease (increase) in:
Increase (Decrease) in Accounts Receivable	15,773	9,254
Increase (Decrease) in Prepaid Expense and Other Assets	370	(4)
Increase (Decrease) in Other Operating Assets	(727)	25
(Decrease) increase in:
Accounts payable and accrued expenses	(23,797)	(12,902)
Income taxes payable	6,360	(1,283)
Deferred revenue	1,250	(1,340)
Liability for uncertain tax positions	1,742	2,595
Other	1,272	(50)
Net Cash Provided by (Used in) Operating Activities	64,524	45,716
Cash flows from investing activities:
Sales of available-for-sale investments	26,224	28,994
Payments to Acquire Available-for-sale Securities	(21,402)	(19,819)
Payments to Acquire Property, Plant, and Equipment	(4,321)	(2,956)
Payments to Acquire Businesses, Net of Cash Acquired	(47,989)	(72,215)
Payments to Acquire Intangible Assets	(316)	(327)
Net Cash Provided by (Used in) Investing Activities	(47,804)	(66,323)
Cash flows from financing activities:
Payments for Repurchase of Common Stock	(1,786)	(705)
Issuance of common stock under employee stock purchase plan	58	61
Exercise of stock options	1,312	65
Payments of Dividends	(15,817)	(14,110)
Excess tax benefits from share-based compensation	264	334
Deferred payments for acquisitions	(14,386)	(2,356)
Proceeds from (Payments for) Other Financing Activities	(25)	(50)
Payments of Distributions to Affiliates	0	0
Net Cash Provided by (Used in) Financing Activities	(30,380)	(16,761)
Effect of exchange rate changes on cash and cash equivalents	885	(4,278)
Cash and Cash Equivalents, Period Increase (Decrease)	(12,775)	(41,646)
Cash and cash equivalents	242,755	392,017	$ 255,530	$ 433,663
j2 Global, Inc. [Member]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	29,943	21,877
(Decrease) increase in:
Net Cash Provided by (Used in) Operating Activities	5,686	(8,106)
Cash flows from investing activities:
Sales of available-for-sale investments	26,224	21,994
Payments to Acquire Available-for-sale Securities	(21,402)	(13,276)
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
Net Cash Provided by (Used in) Investing Activities	4,822	8,718
Cash flows from financing activities:
Payments for Repurchase of Common Stock	(1,786)	(705)
Issuance of common stock under employee stock purchase plan	58	61
Exercise of stock options	1,312	65
Payments of Dividends	(15,817)	(14,110)
Excess tax benefits from share-based compensation	264	334
Deferred payments for acquisitions	0	0
Proceeds from (Payments for) Other Financing Activities	0	0
Payments of Distributions to Affiliates	13,327	13,232
Net Cash Provided by (Used in) Financing Activities	(29,296)	(27,587)
Effect of exchange rate changes on cash and cash equivalents	(91)	0
Cash and Cash Equivalents, Period Increase (Decrease)	(18,879)	(26,975)
Cash and cash equivalents	36,637	199,815	55,516	226,790
j2 Cloud Services, Inc. [Member]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	34,323	26,251
(Decrease) increase in:
Net Cash Provided by (Used in) Operating Activities	(450)	6,745
Cash flows from investing activities:
Sales of available-for-sale investments	0	7,000
Payments to Acquire Available-for-sale Securities	0	(6,543)
Payments to Acquire Property, Plant, and Equipment	(284)	(308)
Payments to Acquire Businesses, Net of Cash Acquired	0	1,459
Payments to Acquire Intangible Assets	0	(5)
Net Cash Provided by (Used in) Investing Activities	(284)	1,603
Cash flows from financing activities:
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	(528)	(544)
Proceeds from (Payments for) Other Financing Activities	0	0
Payments of Distributions to Affiliates	4,147	27,098
Net Cash Provided by (Used in) Financing Activities	(4,675)	(27,642)
Effect of exchange rate changes on cash and cash equivalents	(30)	0
Cash and Cash Equivalents, Period Increase (Decrease)	(5,439)	(19,294)
Cash and cash equivalents	4,536	17,516	9,975	36,810
Non-Guarantor Subsidiaries [Member]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	27,696	23,539
(Decrease) increase in:
Net Cash Provided by (Used in) Operating Activities	59,288	47,077
Cash flows from investing activities:
Sales of available-for-sale investments	0	0
Payments to Acquire Available-for-sale Securities	0	0
Payments to Acquire Property, Plant, and Equipment	(4,037)	(2,648)
Payments to Acquire Businesses, Net of Cash Acquired	(47,989)	(73,674)
Payments to Acquire Intangible Assets	(316)	(322)
Net Cash Provided by (Used in) Investing Activities	(52,342)	(76,644)
Cash flows from financing activities:
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	(13,858)	(1,812)
Proceeds from (Payments for) Other Financing Activities	(25)	(50)
Payments of Distributions to Affiliates	(17,474)	(40,330)
Net Cash Provided by (Used in) Financing Activities	3,591	38,468
Effect of exchange rate changes on cash and cash equivalents	1,006	(4,278)
Cash and Cash Equivalents, Period Increase (Decrease)	11,543	4,623
Cash and cash equivalents	201,582	174,686	190,039	170,063
Consolidation, Eliminations [Member]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	(62,019)	(49,790)
(Decrease) increase in:
Net Cash Provided by (Used in) Operating Activities	0	0
Cash flows from investing activities:
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
Net Cash Provided by (Used in) Investing Activities	0	0
Cash flows from financing activities:
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	$ 0	$ 0