Basis Of Presentation (Policy)	9 Months Ended
Sep. 30, 2019
Accounting Policies [Abstract]
Use Of Estimates	Use of Estimates The preparation of consolidated financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities at the date of the financial statements, including judgments about investment classifications and the reported amounts of net revenue and expenses during the reporting period. The Company believes that its most significant estimates are those related to revenue recognition, valuation and impairment of investments, its assessment of ownership interests as variable interest entities and the related determination of consolidation, share-based compensation expense, assets acquired and liabilities assumed in connection with business combinations, long-lived and intangible asset impairment, contingent consideration, income taxes and contingencies and allowances for doubtful accounts. On an ongoing basis, management evaluates its estimates based on historical experience and on various other factors that the Company believes to be reasonable under the circumstances. Actual results could materially differ from those estimates.
Allowances For Doubtful Accounts	Allowances for Doubtful Accounts J2 Global reserves for receivables it may not be able to collect. The reserves for the Company’s Cloud Services business are typically driven by the volume of credit card declines and past due invoices and are based on historical experience as well as an evaluation of current market conditions. The reserves for the Company’s Digital Media business are typically driven by past due invoices based on historical experience. On an ongoing basis, management evaluates the adequacy of these reserves.
Revenue [Policy Text Block]	Revenue Recognition J2 Global recognizes revenue when the Company satisfies its obligation by transferring control of the goods or services to its customers in an amount that reflects the consideration to which the Company expects to be entitled in exchange for those goods or services (see Note 3 - Revenues). Principal vs. Agent The Company determines whether revenue should be reported on a gross or net basis by assessing whether the Company is acting as the principal or an agent in the transaction. If the Company is acting as the principal in a transaction, the Company reports revenue on a gross basis. If the Company is acting as an agent in a transaction, the Company reports revenue on a net basis. In determining whether the Company acts as the principal or an agent, the Company follows the accounting guidance under Topic 606 for principal-agent considerations and assesses: (i) if another party is involved in providing goods or services to the customer and (ii) whether the Company controls the specified goods or services prior to transferring control to the customer. Sales Taxes The Company has made an accounting policy election to exclude from the measurement of the transaction price all taxes assessed by a governmental authority that are (i) both imposed on and concurrent with a specific revenue-producing transaction and (ii) collected by the Company from a customer.
Fair Value of Financial Instruments, Policy [Policy Text Block]	Fair Value Measurements J2 Global complies with the provisions of the Financial Accounting Standards Board (“FASB”) ASC Topic No. 820, Fair Value Measurements and Disclosures (“ASC 820”), in measuring fair value and in disclosing fair value measurements. ASC 820 provides a framework for measuring fair value and expands the disclosures required for fair value measurements of financial and non-financial assets and liabilities. As of September 30, 2019, the carrying value of cash and cash equivalents, accounts receivable, interest receivable, accounts payable, accrued expenses, interest payable, customer deposits and long-term debt are reflected in the financial statements at cost. With the exception of certain investments and long-term debt, cost approximates fair value due to the short-term nature of such instruments. The fair value of the Company’s outstanding debt was determined using the quoted market prices of available debt instruments with similar terms and maturities. As of the same dates, the carrying value of other long-term liabilities approximated fair value as the related interest rates approximate rates currently available to J2 Global.
Investment, Policy [Policy Text Block]	Investments The Company accounts for its investments in debt securities in accordance with ASC Topic No. 320, Investments - Debt Securities (“ASC 320”). Debt investments are typically comprised of corporate debt securities. J2 Global determines the appropriate classification of its investments at the time of acquisition and evaluates such determination at each balance sheet date. Trading securities are those investments that the Company intends to sell within a few hours or days and are carried at fair value, with unrealized gains and losses included in investment income. Available-for-sale debt securities are those investments J2 Global does not intend to hold to maturity and can be sold. Available-for-sale securities are carried at fair value with unrealized gains and losses included in other comprehensive income. Held-to-maturity securities are those investments which the Company has the ability and intent to hold until maturity and are recorded at amortized cost. All debt securities are accounted for on a specific identification basis. The Company accounts for its investments in equity securities in accordance with ASC Topic No. 321, Investments - Equity Securities (“ASC 321”) which requires the accounting for equity investments (other than those accounted for using the equity method of accounting) generally be measured at fair value for equity securities with readily determinable fair values. For equity securities without a readily determinable fair value that are not accounted for by the equity method, the Company measures the equity security using cost, less impairment, if any, and plus or minus observable price changes arising from orderly transactions in the same or similar investment from the same issuer. Any unrealized gains or losses will be reported in current earnings (see Note 5 - Investments). Variable Interest Entities (“VIE”) A VIE requires consolidation by the entity’s primary beneficiary. The Company evaluates its investments in entities in which it is involved to determine if the entity is a VIE and if so, whether it holds a variable interest and is the primary beneficiary. The Company has determined that it holds a variable interest in its investment as a limited partner in the OCV Fund I, LP (“OCV Fund”, “OCV” or the “Fund”). In determining whether the Company is deemed to be the primary beneficiary of the VIE, both of the following characteristics must be present: a) the Company has the power to direct the activities of the VIE that most significantly impacts the VIEs economic performance (the power criterion); and b) the Company has the obligation to absorb losses of the VIE, or the right to receive benefits of the VIE, that could potentially be significant to the VIE (the economic criterion). The Company has concluded that, as a limited partner, although the obligations to absorb losses or benefit from the gains is not insignificant, the Company does not have “power” over OCV because it does not have the ability to direct the significant decisions which impact the economics of OCV. J2 believes that the OCV general partner, as a single decision maker, holds the ability to make the decisions about the activities that most significantly impacts the OCV Fund’s economic performance. As a result, the Company has concluded that it will not consolidate OCV, as it is not the primary beneficiary of the OCV Fund, and will account for this investment under the equity-method of accounting. See Note 5, “Investments”. OCV qualifies as an investment company under ASC 946 - Financial Services, Investment Companies (“ASC 946”). Under ASC Topic 323, Investments - Equity Method and Joint Ventures, an investor that holds investments that qualify for specialized industry accounting for investment companies in accordance with ASC 946 should record its share of the earnings or losses, realized or unrealized, as reported by its equity method investees in the Condensed Consolidated Statements of Income. The Company recognizes its equity in the net earnings or losses relating to the investment in OCV on a one-quarter lag due to the timing and availability of financial information from OCV. If the Company becomes aware of a significant decline in value that is other-than-temporary, the loss will be recorded in the period in which the Company identifies the decline.
Debt	Debt Issuance Costs and Debt Discount J2 Global capitalizes costs incurred with borrowing and issuance of debt securities and records debt issuance costs and discounts as a reduction to the debt amount. These costs and discounts are amortized and included in interest expense over the life of the borrowing using the effective interest method. Debt issuance costs associated with entering into the Credit Facility are recorded on the Condensed Consolidated Balance Sheets as an asset and amortized and included in interest expense over the contractual term of the Credit Agreement.
Property, Plant and Equipment, Policy [Policy Text Block]	Property and Equipment Property and equipment are stated at cost. Equipment under capital leases is stated at the present value of the minimum lease payments. Depreciation is calculated using the straight-line method over the estimated useful lives of the assets. The estimated useful lives of property and equipment range from 1 to 10 years. Fixtures, which are comprised primarily of leasehold improvements and equipment under capital leases, are amortized on a straight-line basis over their estimated useful lives or for leasehold improvements, the related lease term, if less. The Company has capitalized certain internal use software and website development costs which are included in property and equipment. The estimated useful life of costs capitalized is evaluated for each specific project and ranges from 1 to 5 years.
Business Combinations Policy [Policy Text Block]	Contingent Consideration J2 Global measures the contingent earn-out liabilities in connection with acquisitions at fair value on a recurring basis using significant unobservable inputs classified within Level 3 of the fair value hierarchy (see Note 6 - Fair Value Measurements). The Company may use various valuation techniques depending on the terms and conditions of the contingent consideration including a Monte-Carlo simulation. This simulation uses a probability distribution for each significant input to produce hundreds or thousands of possible outcomes and the results are analyzed to determine probabilities of different outcomes occurring. Significant increases or decreases to these inputs in isolation would result in a significantly higher or lower liability with a higher liability capped by the contractual maximum of the contingent earn-out obligation. Ultimately, the liability will be equivalent to the amount paid, and the difference between the fair value estimate and the amount paid will be recorded in earnings. The amount paid that is less than or equal to the liability on the acquisition date is reflected as cash used in financing activities in our consolidated statements of cash flows. Any amount paid in excess of the liability on the acquisition date is reflected as cash used in operating activities. J2 Global reviews and re-assesses the estimated fair value of contingent consideration on a quarterly basis, and the updated fair value could be materially different from the initial estimates or prior quarterly amounts. Changes in the estimated fair value of our contingent earn-out liabilities are reported in operating income. Adjustments to the estimated fair value related to changes in all other unobservable inputs are reported in operating income.
Self Insurance Reserve [Policy Text Block]	Self-Insurance Program J2 Global provides health and dental insurance plans for certain of its employees through a self-insurance structure. The Company has secured reinsurance in the form of a two tiered stop-loss coverage that limits the exposure arising from any claims made. Self-insurance claims filed and claims incurred but not reported are accrued based on management’s estimate of the discounted ultimate costs for self-insured claims incurred using actuarial assumptions followed in the insurance industry and historical experience. Although management believes it has the ability to reasonably estimate losses related to claims, it is possible that actual results could materially differ from recorded self-insurance liabilities.
Segment Reporting	Segment Reporting Accounting guidance establishes standards for the way that public business enterprises report information about operating segments in their annual consolidated financial statements and requires that those enterprises report selected information about operating segments in interim financial reports. Accounting guidance also establishes standards for related disclosures about products and services, geographic areas and major customers. The Company’s business segments are based on the organization structure used by the chief operating decision maker for making operating and investment decisions and for assessing performance. The chief operating decision maker views the Company in two businesses: Cloud Services and Digital Media. However, in accordance with the aggregation criteria within the accounting guidance, J2 Global’s operating segments have been aggregated into three reportable segments: (i) Fax and Martech (formerly Email Marketing); (ii) Voice, Backup, Security, and Consumer Privacy and Protection; and (iii) Digital Media.
Comparability of Prior Year Financial Data	Reclassifications Certain prior year reported amounts have been reclassified to conform to the 2019 presentation.

Basis Of Presentation (Policy)

9 Months Ended

Sep. 30, 2019

Use of Estimates

The preparation of consolidated financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities at the date of the financial statements, including judgments about investment classifications and the reported amounts of net revenue and expenses during the reporting period. The Company believes that its most significant estimates are those related to revenue recognition, valuation and impairment of investments, its assessment of ownership interests as variable interest entities and the related determination of consolidation, share-based compensation expense, assets acquired and liabilities assumed in connection with business combinations, long-lived and intangible asset impairment, contingent consideration, income taxes and contingencies and allowances for doubtful accounts. On an ongoing basis, management evaluates its estimates based on historical experience and on various other factors that the Company believes to be reasonable under the circumstances. Actual results could materially differ from those estimates.

Allowances For Doubtful Accounts

Allowances for Doubtful Accounts

J2 Global reserves for receivables it may not be able to collect. The reserves for the Company’s Cloud Services business are typically driven by the volume of credit card declines and past due invoices and are based on historical experience as well as an evaluation of current market conditions. The reserves for the Company’s Digital Media business are typically driven by past due invoices based on historical experience. On an ongoing basis, management evaluates the adequacy of these reserves.

Revenue [Policy Text Block]

Revenue Recognition

J2 Global recognizes revenue when the Company satisfies its obligation by transferring control of the goods or services to its customers in an amount that reflects the consideration to which the Company expects to be entitled in exchange for those goods or services (see Note 3 - Revenues).

Principal vs. Agent

The Company determines whether revenue should be reported on a gross or net basis by assessing whether the Company is acting as the principal or an agent in the transaction. If the Company is acting as the principal in a transaction, the Company

reports revenue on a gross basis. If the Company is acting as an agent in a transaction, the Company reports revenue on a net basis. In determining whether the Company acts as the principal or an agent, the Company follows the accounting guidance under Topic 606 for principal-agent considerations and assesses: (i) if another party is involved in providing goods or services to the customer and (ii) whether the Company controls the specified goods or services prior to transferring control to the customer.

Sales Taxes

The Company has made an accounting policy election to exclude from the measurement of the transaction price all taxes assessed by a governmental authority that are (i) both imposed on and concurrent with a specific revenue-producing transaction and (ii) collected by the Company from a customer.

Fair Value of Financial Instruments, Policy [Policy Text Block]

Fair Value Measurements

J2 Global complies with the provisions of the Financial Accounting Standards Board (“FASB”) ASC Topic No. 820, Fair Value Measurements and Disclosures (“ASC 820”), in measuring fair value and in disclosing fair value measurements. ASC 820 provides a framework for measuring fair value and expands the disclosures required for fair value measurements of financial and non-financial assets and liabilities.

As of September 30, 2019, the carrying value of cash and cash equivalents, accounts receivable, interest receivable, accounts payable, accrued expenses, interest payable, customer deposits and long-term debt are reflected in the financial statements at cost. With the exception of certain investments and long-term debt, cost approximates fair value due to the short-term nature of such instruments. The fair value of the Company’s outstanding debt was determined using the quoted market prices of available debt instruments with similar terms and maturities. As of the same dates, the carrying value of other long-term liabilities approximated fair value as the related interest rates approximate rates currently available to J2 Global.

Investment, Policy [Policy Text Block]

Investments

The Company accounts for its investments in debt securities in accordance with ASC Topic No. 320, Investments - Debt Securities (“ASC 320”). Debt investments are typically comprised of corporate debt securities. J2 Global determines the appropriate classification of its investments at the time of acquisition and evaluates such determination at each balance sheet date. Trading securities are those investments that the Company intends to sell within a few hours or days and are carried at fair value, with unrealized gains and losses included in investment income. Available-for-sale debt securities are those investments J2 Global does not intend to hold to maturity and can be sold. Available-for-sale securities are carried at fair value with unrealized gains and losses included in other comprehensive income. Held-to-maturity securities are those investments which the Company has the ability and intent to hold until maturity and are recorded at amortized cost. All debt securities are accounted for on a specific identification basis.

The Company accounts for its investments in equity securities in accordance with ASC Topic No. 321, Investments - Equity Securities (“ASC 321”) which requires the accounting for equity investments (other than those accounted for using the equity method of accounting) generally be measured at fair value for equity securities with readily determinable fair values. For equity securities without a readily determinable fair value that are not accounted for by the equity method, the Company measures the equity security using cost, less impairment, if any, and plus or minus observable price changes arising from orderly transactions in the same or similar investment from the same issuer. Any unrealized gains or losses will be reported in current earnings (see Note 5 - Investments).

Variable Interest Entities (“VIE”)

A VIE requires consolidation by the entity’s primary beneficiary. The Company evaluates its investments in entities in which it is involved to determine if the entity is a VIE and if so, whether it holds a variable interest and is the primary beneficiary. The Company has determined that it holds a variable interest in its investment as a limited partner in the OCV Fund I, LP (“OCV Fund”, “OCV” or the “Fund”). In determining whether the Company is deemed to be the primary beneficiary of the VIE, both of the following characteristics must be present:

a) the Company has the power to direct the activities of the VIE that most significantly impacts the VIEs economic performance (the power criterion); and

b) the Company has the obligation to absorb losses of the VIE, or the right to receive benefits of the VIE, that could potentially be significant to the VIE (the economic criterion).

The Company has concluded that, as a limited partner, although the obligations to absorb losses or benefit from the gains is not insignificant, the Company does not have “power” over OCV because it does not have the ability to direct the significant decisions which impact the economics of OCV. J2 believes that the OCV general partner, as a single decision maker, holds the ability to make the decisions about the activities that most significantly impacts the OCV Fund’s economic performance. As a result, the Company has concluded that it will not consolidate OCV, as it is not the primary beneficiary of the OCV Fund, and will account for this investment under the equity-method of accounting. See Note 5, “Investments”.

OCV qualifies as an investment company under ASC 946 - Financial Services, Investment Companies (“ASC 946”). Under ASC Topic 323, Investments - Equity Method and Joint Ventures, an investor that holds investments that qualify for specialized industry accounting for investment companies in accordance with ASC 946 should record its share of the earnings or losses, realized or unrealized, as reported by its equity method investees in the Condensed Consolidated Statements of Income.

The Company recognizes its equity in the net earnings or losses relating to the investment in OCV on a one-quarter lag due to the timing and availability of financial information from OCV. If the Company becomes aware of a significant decline in value that is other-than-temporary, the loss will be recorded in the period in which the Company identifies the decline.

Debt

Debt Issuance Costs and Debt Discount

J2 Global capitalizes costs incurred with borrowing and issuance of debt securities and records debt issuance costs and discounts as a reduction to the debt amount. These costs and discounts are amortized and included in interest expense over the life of the borrowing using the effective interest method. Debt issuance costs associated with entering into the Credit Facility are recorded on the Condensed Consolidated Balance Sheets as an asset and amortized and included in interest expense over the contractual term of the Credit Agreement.

Property, Plant and Equipment, Policy [Policy Text Block]

Property and Equipment

Property and equipment are stated at cost. Equipment under capital leases is stated at the present value of the minimum lease payments. Depreciation is calculated using the straight-line method over the estimated useful lives of the assets. The estimated useful lives of property and equipment range from 1 to 10 years. Fixtures, which are comprised primarily of leasehold improvements and equipment under capital leases, are amortized on a straight-line basis over their estimated useful lives or for leasehold improvements, the related lease term, if less. The Company has capitalized certain internal use software and website development costs which are included in property and equipment. The estimated useful life of costs capitalized is evaluated for each specific project and ranges from 1 to 5 years.

Business Combinations Policy [Policy Text Block]

Contingent Consideration

J2 Global measures the contingent earn-out liabilities in connection with acquisitions at fair value on a recurring basis using significant unobservable inputs classified within Level 3 of the fair value hierarchy (see Note 6 - Fair Value Measurements). The Company may use various valuation techniques depending on the terms and conditions of the contingent consideration including a Monte-Carlo simulation. This simulation uses a probability distribution for each significant input to produce hundreds or thousands of possible outcomes and the results are analyzed to determine probabilities of different outcomes occurring. Significant increases or decreases to these inputs in isolation would result in a significantly higher or lower liability with a higher liability capped by the contractual maximum of the contingent earn-out obligation. Ultimately, the liability will be equivalent to the amount paid, and the difference between the fair value estimate and the amount paid will be recorded in earnings. The amount paid that is less than or equal to the liability on the acquisition date is reflected as cash used in financing activities in our consolidated statements of cash flows. Any amount paid in excess of the liability on the acquisition date is reflected as cash used in operating activities.

J2 Global reviews and re-assesses the estimated fair value of contingent consideration on a quarterly basis, and the updated fair value could be materially different from the initial estimates or prior quarterly amounts. Changes in the estimated fair value of our contingent earn-out liabilities are reported in operating income. Adjustments to the estimated fair value related to changes in all other unobservable inputs are reported in operating income.

Self Insurance Reserve [Policy Text Block]

Self-Insurance Program

J2 Global provides health and dental insurance plans for certain of its employees through a self-insurance structure. The Company has secured reinsurance in the form of a two tiered stop-loss coverage that limits the exposure arising from any claims made. Self-insurance claims filed and claims incurred but not reported are accrued based on management’s estimate of the discounted ultimate costs for self-insured claims incurred using actuarial assumptions followed in the insurance industry and historical experience. Although management believes it has the ability to reasonably estimate losses related to claims, it is possible that actual results could materially differ from recorded self-insurance liabilities.

Segment Reporting

Accounting guidance establishes standards for the way that public business enterprises report information about operating segments in their annual consolidated financial statements and requires that those enterprises report selected information about operating segments in interim financial reports. Accounting guidance also establishes standards for related disclosures about products and services, geographic areas and major customers. The Company’s business segments are based on the organization structure used by the chief operating decision maker for making operating and investment decisions and for assessing performance. The chief operating decision maker views the Company in two businesses: Cloud Services and Digital Media. However, in accordance with the aggregation criteria within the accounting guidance, J2 Global’s operating segments have been aggregated into three reportable segments: (i) Fax and Martech (formerly Email Marketing); (ii) Voice, Backup, Security, and Consumer Privacy and Protection; and (iii) Digital Media.

Comparability of Prior Year Financial Data

Reclassifications

Certain prior year reported amounts have been reclassified to conform to the 2019 presentation.