Summary of Significant Accounting Policies (Notes)	9 Months Ended
Sep. 30, 2018
Accounting Policies [Abstract]
Significant Accounting Policies	Note 2: Summary of Significant Accounting Policies Effective January 1, 2018, IPG adopted Accounting Standards Codification Topic 606, Revenue from Contracts with Customers, ("ASC 606") using the full retrospective transition method. Under this method, the Company will revise its consolidated financial statements for the years ended December 31, 2016 and 2017, and applicable interim periods within the year ended December 31, 2017, as if ASC 606 had been effective for those periods. ASC 606 applies to all contracts with customers, except for contracts that are within the scope of other standards. Under ASC 606, an entity recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration which the entity expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that an entity determines are within the scope of ASC 606, we perform the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the entity satisfies a performance obligation. We only apply the five-step model to contracts when it is probable that IPG will collect the consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, once the contract is determined to be within the scope of ASC 606, we assess the goods or services promised within each contract and determine those that are distinct performance obligations. We then assess whether IPG acts as an agent or a principal for each identified performance obligation and include revenue within the transaction price for third-party costs when we determine that we act as principal. Revenue Recognition We recognize revenue when the control to promised goods or services transfers to customers in an amount that reflects the consideration to which we expect to be entitled in exchange for those goods and services. Our revenues are primarily derived from the planning and execution of multi-channel advertising and communications and marketing services, including public relations, meeting and event production, sports and entertainment marketing, corporate and brand identity, and strategic marketing consulting around the world. Our revenues are directly dependent upon the advertising, marketing and corporate communications requirements of our existing clients and our ability to win new clients. Depending on the terms of the client contract, revenue is derived from diverse arrangements involving fees for services performed, commissions, performance incentive provisions and combinations of the three. Net revenue, primarily consisting of fees, commissions and performance incentives, represents the amount of our gross billings excluding pass-through expenses charged to a client. Revenues for the creation, planning and placement of advertising are determined primarily on a negotiated fee basis and, to a lesser extent, on a commission basis. Fees are usually calculated to reflect hourly rates plus proportional overhead and a mark-up. Contractual arrangements with clients may also include performance incentive provisions designed to link a portion of our revenue to our performance relative to mutually agreed-upon qualitative or quantitative metrics, or both. Commissions are earned based on services provided and are usually derived from a percentage or fee over the total cost to complete the assignment. Commissions can also be derived when clients pay us the gross rate billed by media and we pay for media at a lower net rate; the difference is the commission that we earn, which we either retain in full or share with the client depending on the nature of the applicable services agreement. We also generate revenue in negotiated fees from our public relations, sales promotion, event marketing, sports and entertainment marketing, and corporate and brand identity services. Billable expenses predominantly include pass-through expenses related to event and advertising production costs for performance obligations where we have determined that we are acting as principal that are rebilled to our clients, as well as out-of-pocket costs. Out-of-pocket costs often include expenses related to airfare, mileage, hotel stays, out-of-town meals and telecommunication charges for client service staff. We record these billable expenses within total revenue with a corresponding offset to operating expenses. Most of our client contracts are individually negotiated and, accordingly, the terms of client engagements and the basis on which we earn fees and commissions vary significantly. As is customary in the industry, our contracts generally provide for termination by either party on relatively short notice, usually 30 to 90 days. Our payment terms vary by client, and the time between invoicing date and due date is typically not significant. We generally have right to payment for all services provided through the end of the contract or termination date. Our client contracts may include provisions for incentive compensation and vendor rebates and credits. Our largest clients are multinational entities and, as such, we often provide services to these clients out of multiple offices and across many of our agencies. In arranging for such services, it is possible that we will enter into global, regional and local agreements. Agreements of this nature are reviewed by legal counsel to determine the governing terms to be followed by the offices and agencies involved. For media contracts that can be canceled by the customer at any time without compensation, the entity does not have an enforceable right to the payment until media airs, at which point revenue is recognized. Timing of Recognition We have determined that we generally satisfy our performance obligations over time, except for certain less-frequent commission-based contracts, which are recognized at a point in time, typically the date of broadcast or publication. Fees are generally recognized based on proportional performance utilizing periodically updated estimates to complete. Performance Obligations Our client contracts may include various goods and services that are capable of being distinct, are distinct within the context of the contract and are therefore accounted for as separate performance obligations. We allocate revenue to each performance obligation in the contract at inception based on its relative standalone selling price. Our events businesses include creative services related to the conception and planning of custom marketing events as well as activation services which entail the carrying out of the event, including, but not limited to, set-up, design and staffing. Additionally, our public relations businesses include a broad range of services, such as strategic planning, social media strategy and the monitoring and development of communication strategies, among others. While our contracts in these businesses may include some or all of these services, we typically identify only one performance obligation in the assessment of our events and public relations contracts as there is a significant integration of these services into a combined output such that they are not distinct within the context of the contract. Principal vs. Agent For each identified performance obligation in the contract with the customer, we assess whether our agency or the third-party supplier is the principal or agent. We control the specified services before transferring those services to the customer and act as the principal if we are primarily responsible for the integration of products and services into the deliverable to our customer, have inventory risk, or discretion in establishing pricing. For performance obligations in which we act as principal, we record the gross amount billed to the customer within total revenue and the related incremental direct costs incurred as billable expenses. We have determined that we primarily act as principal for creative, media planning, in-house production, event, public relations and branding services, where we control the specified services before transferring those services to the customer because we are primarily responsible for the integration of products and services into the deliverable to our customer. We generally do not have inventory risk or discretion in establishing pricing in our contracts with customers. If the third-party supplier, rather than IPG, is primarily responsible for the performance and deliverable to our customer, then we generally act as the agent and solely arrange for the third-party supplier to provide services to the customer. For performance obligations for which we act as the agent, we record our revenue as the net amount of our gross billings less pass-through expenses charged to a customer. Variable Consideration Revenue for our services is measured based on the consideration specified in a contract with a customer. Contractual arrangements with clients may also include performance incentive provisions designed to link a portion of our revenue to our performance relative to either qualitative or quantitative metrics, or both. Incentive compensation is estimated using the most likely amount and is included in revenue up to the amount that is not expected to result in a reversal of a significant amount of cumulative revenue recognized. We recognize revenue related to performance incentives as we satisfy the performance obligation to which performance incentives are related. Practical Expedients As part of our adoption of ASC 606, we apply the practical expedient and do not disclose information about remaining performance obligations that have original expected durations of one year or less. Amounts related to those performance obligations with expected durations of greater than one year are immaterial. We apply the practical expedient and do not capitalize costs to obtain a contract as these amounts would generally be recognized over less than one year and are not material. Additionally, we report revenue net of taxes assessed by governmental authorities that are directly imposed on our revenue-producing transactions.

Note 2: Summary of Significant Accounting Policies

Effective January 1, 2018, IPG adopted Accounting Standards Codification Topic 606, Revenue from Contracts with Customers, ("ASC 606") using the full retrospective transition method. Under this method, the Company will revise its consolidated financial statements for the years ended December 31, 2016 and 2017, and applicable interim periods within the year ended December 31, 2017, as if ASC 606 had been effective for those periods. ASC 606 applies to all contracts with customers, except for contracts that are within the scope of other standards. Under ASC 606, an entity recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration which the entity expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that an entity determines are within the scope of ASC 606, we perform the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the entity satisfies a performance obligation. We only apply the five-step model to contracts when it is probable that IPG will collect the consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, once the contract is determined to be within the scope of ASC 606, we assess the goods or services promised within each contract and determine those that are distinct performance obligations. We then assess whether IPG acts as an agent or a principal for each identified performance obligation and include revenue within the transaction price for third-party costs when we determine that we act as principal.

Revenue Recognition

We recognize revenue when the control to promised goods or services transfers to customers in an amount that reflects the consideration to which we expect to be entitled in exchange for those goods and services. Our revenues are primarily derived from the planning and execution of multi-channel advertising and communications and marketing services, including public relations, meeting and event production, sports and entertainment marketing, corporate and brand identity, and strategic marketing consulting around the world. Our revenues are directly dependent upon the advertising, marketing and corporate communications requirements of our existing clients and our ability to win new clients. Depending on the terms of the client contract, revenue is derived from diverse arrangements involving fees for services performed, commissions, performance incentive provisions and combinations of the three.

Net revenue, primarily consisting of fees, commissions and performance incentives, represents the amount of our gross billings excluding pass-through expenses charged to a client. Revenues for the creation, planning and placement of advertising are determined primarily on a negotiated fee basis and, to a lesser extent, on a commission basis. Fees are usually calculated to reflect hourly rates plus proportional overhead and a mark-up. Contractual arrangements with clients may also include performance incentive provisions designed to link a portion of our revenue to our performance relative to mutually agreed-upon qualitative or quantitative metrics, or both. Commissions are earned based on services provided and are usually derived from a percentage or fee over the total cost to complete the assignment. Commissions can also be derived when clients pay us the gross rate billed by media and we pay for media at a lower net rate; the difference is the commission that we earn, which we either retain in full or share with the client depending on the nature of the applicable services agreement. We also generate revenue in negotiated fees from our public relations, sales promotion, event marketing, sports and entertainment marketing, and corporate and brand identity services.

Billable expenses predominantly include pass-through expenses related to event and advertising production costs for performance obligations where we have determined that we are acting as principal that are rebilled to our clients, as well as out-of-pocket costs. Out-of-pocket costs often include expenses related to airfare, mileage, hotel stays, out-of-town meals and telecommunication charges for client service staff. We record these billable expenses within total revenue with a corresponding offset to operating expenses.

Most of our client contracts are individually negotiated and, accordingly, the terms of client engagements and the basis on which we earn fees and commissions vary significantly. As is customary in the industry, our contracts generally provide for termination by either party on relatively short notice, usually 30 to 90 days. Our payment terms vary by client, and the time between invoicing date and due date is typically not significant. We generally have right to payment for all services provided through the end of the contract or termination date.

Our client contracts may include provisions for incentive compensation and vendor rebates and credits. Our largest clients are multinational entities and, as such, we often provide services to these clients out of multiple offices and across many of our agencies. In arranging for such services, it is possible that we will enter into global, regional and local agreements. Agreements of this nature are reviewed by legal counsel to determine the governing terms to be followed by the offices and agencies involved.

For media contracts that can be canceled by the customer at any time without compensation, the entity does not have an enforceable right to the payment until media airs, at which point revenue is recognized.

Timing of Recognition

We have determined that we generally satisfy our performance obligations over time, except for certain less-frequent commission-based contracts, which are recognized at a point in time, typically the date of broadcast or publication. Fees are generally recognized based on proportional performance utilizing periodically updated estimates to complete.

Performance Obligations

Our client contracts may include various goods and services that are capable of being distinct, are distinct within the context of the contract and are therefore accounted for as separate performance obligations. We allocate revenue to each performance obligation in the contract at inception based on its relative standalone selling price. Our events businesses include creative services related to the conception and planning of custom marketing events as well as activation services which entail the carrying out of the event, including, but not limited to, set-up, design and staffing. Additionally, our public relations businesses include a broad range of services, such as strategic planning, social media strategy and the monitoring and development of communication strategies, among others. While our contracts in these businesses may include some or all of these services, we typically identify only one performance obligation in the assessment of our events and public relations contracts as there is a significant integration of these services into a combined output such that they are not distinct within the context of the contract.

Principal vs. Agent

For each identified performance obligation in the contract with the customer, we assess whether our agency or the third-party supplier is the principal or agent. We control the specified services before transferring those services to the customer and act as the principal if we are primarily responsible for the integration of products and services into the deliverable to our customer, have inventory risk, or discretion in establishing pricing. For performance obligations in which we act as principal, we record the gross amount billed to the customer within total revenue and the related incremental direct costs incurred as billable expenses. We have determined that we primarily act as principal for creative, media planning, in-house production, event, public relations and branding services, where we control the specified services before transferring those services to the customer because we are primarily responsible for the integration of products and services into the deliverable to our customer. We generally do not have inventory risk or discretion in establishing pricing in our contracts with customers.

If the third-party supplier, rather than IPG, is primarily responsible for the performance and deliverable to our customer, then we generally act as the agent and solely arrange for the third-party supplier to provide services to the customer. For performance obligations for which we act as the agent, we record our revenue as the net amount of our gross billings less pass-through expenses charged to a customer.

Variable Consideration

Revenue for our services is measured based on the consideration specified in a contract with a customer. Contractual arrangements with clients may also include performance incentive provisions designed to link a portion of our revenue to our performance relative to either qualitative or quantitative metrics, or both.

Incentive compensation is estimated using the most likely amount and is included in revenue up to the amount that is not expected to result in a reversal of a significant amount of cumulative revenue recognized. We recognize revenue related to performance incentives as we satisfy the performance obligation to which performance incentives are related.

Practical Expedients

As part of our adoption of ASC 606, we apply the practical expedient and do not disclose information about remaining performance obligations that have original expected durations of one year or less. Amounts related to those performance obligations with expected durations of greater than one year are immaterial.

We apply the practical expedient and do not capitalize costs to obtain a contract as these amounts would generally be recognized over less than one year and are not material.

Additionally, we report revenue net of taxes assessed by governmental authorities that are directly imposed on our revenue-producing transactions.