Commitments and Contingencies (Notes)	3 Months Ended
Mar. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Legal Matters We are involved in various legal proceedings, and subject to investigations, inspections, audits, inquiries and similar actions by governmental authorities, arising in the normal course of business. The types of allegations that arise in connection with such legal proceedings may vary in nature, but can include claims related to contract, employment, tax and intellectual property matters. We evaluate all cases each reporting period and record liabilities for losses from legal proceedings when we determine that it is probable that the outcome in a legal proceeding will be unfavorable and the amount, or potential range, of loss can be reasonably estimated. In certain cases, we cannot reasonably estimate the potential loss because, for example, the litigation is in its early stages. While any outcome related to litigation or such governmental proceedings in which we are involved cannot be predicted with certainty, management believes that the outcome of these matters, individually and in the aggregate, will not have a material adverse effect on our financial condition, results of operations or cash flows. As previously disclosed, on April 10, 2015, a federal judge in Brazil authorized the search of the records of an agency's offices in São Paulo and Brasilia, in connection with an ongoing investigation by Brazilian authorities involving payments potentially connected to local government contracts. The Company had previously investigated the matter and taken a number of remedial and disciplinary actions. The Company has been in the process of concluding a settlement related to these matters with government agencies, and that settlement was fully executed in April 2018. The Company has previously provided for such settlement in its Consolidated Financial Statements. In December 2016, one of the Company's standalone domestic agencies was contacted by the Department of Justice Antitrust Division for documents regarding video production practices and is cooperating with the government. Guarantees As discussed in our 2017 Annual Report on Form 10-K, we have guaranteed certain obligations of our subsidiaries relating principally to operating leases, uncommitted lines of credit and cash pooling arrangements. As of March 31, 2018 and December 31, 2017, the amount of parent company guarantees on lease obligations was $822.6 and $829.2, respectively, the amount of parent company guarantees relating to uncommitted lines of credit was $329.6 and $308.8, respectively, and the amount of parent company guarantees related to daylight overdrafts, primarily utilized to manage intra-day overdrafts due to timing of transactions under cash pooling arrangements without resulting in incremental borrowings, was $205.5 and $182.2, respectively.

Commitments and Contingencies

Legal Matters

We are involved in various legal proceedings, and subject to investigations, inspections, audits, inquiries and similar actions by governmental authorities, arising in the normal course of business. The types of allegations that arise in connection with such legal proceedings may vary in nature, but can include claims related to contract, employment, tax and intellectual property matters. We evaluate all cases each reporting period and record liabilities for losses from legal proceedings when we determine that it is probable that the outcome in a legal proceeding will be unfavorable and the amount, or potential range, of loss can be reasonably estimated. In certain cases, we cannot reasonably estimate the potential loss because, for example, the litigation is in its early stages. While any outcome related to litigation or such governmental proceedings in which we are involved cannot be predicted with certainty, management believes that the outcome of these matters, individually and in the aggregate, will not have a material adverse effect on our financial condition, results of operations or cash flows.

As previously disclosed, on April 10, 2015, a federal judge in Brazil authorized the search of the records of an agency's offices in São Paulo and Brasilia, in connection with an ongoing investigation by Brazilian authorities involving payments potentially connected to local government contracts. The Company had previously investigated the matter and taken a number of remedial and disciplinary actions. The Company has been in the process of concluding a settlement related to these matters with government agencies, and that settlement was fully executed in April 2018. The Company has previously provided for such settlement in its Consolidated Financial Statements.

In December 2016, one of the Company's standalone domestic agencies was contacted by the Department of Justice Antitrust Division for documents regarding video production practices and is cooperating with the government.

Guarantees

As discussed in our 2017 Annual Report on Form 10-K, we have guaranteed certain obligations of our subsidiaries relating principally to operating leases, uncommitted lines of credit and cash pooling arrangements. As of March 31, 2018 and December 31, 2017, the amount of parent company guarantees on lease obligations was $822.6 and $829.2, respectively, the amount of parent company guarantees relating to uncommitted lines of credit was $329.6 and $308.8, respectively, and the amount of parent company guarantees related to daylight overdrafts, primarily utilized to manage intra-day overdrafts due to timing of transactions under cash pooling arrangements without resulting in incremental borrowings, was $205.5 and $182.2, respectively.