Basis of Presentation and Accounting Policies (Policies)	9 Months Ended
Sep. 30, 2019
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation Certain information and footnote disclosures normally included in the financial statements prepared in accordance with United States Generally Accepted Accounting Principles ("GAAP") have been condensed or omitted pursuant to the rules and regulations of the Securities and Exchange Commission, although we believe that the disclosures are adequate to make the information presented not misleading. These Consolidated Financial Statements should be read in conjunction with the Consolidated Financial Statements included in our 2018 Annual Report on Form 10-K. The information furnished reflects all adjustments that, in the opinion of management, were necessary for a fair statement of the Consolidated Financial Statements for the periods presented. Such adjustments were of a normal recurring nature, unless otherwise disclosed.
Leases	Leases We determine whether a contract is or contains a lease at contract inception. Right-of-use (“ROU”) assets and long-term lease liabilities are presented as separate line items on our Consolidated Balance Sheets. Current operating lease liabilities are included in accrued expenses on our Consolidated Balance Sheets. ROU assets represent our right to use an underlying asset for the lease term and lease liabilities represent our obligation to make lease payments arising from the lease. Lease liabilities are recognized at commencement date based on the present value of remaining lease payments over the lease term. As the rate implicit in the lease is not readily determinable in most of our leases, we use our incremental borrowing rate. We determine our incremental borrowing rate at the commencement date using our unsecured borrowing rate, adjusted for collaterization, lease term, economic environment, currency and other factors. ROU assets are recognized at commencement date at the value of the related lease liabilities, adjusted for any prepayments, lease incentives received, and initial direct costs incurred. Our lease terms include options to renew or not terminate the lease when it is reasonably certain that we will exercise that option. Lease expenses for operating leases are recognized on a straight-line basis over the lease term and recorded in selling and administrative expenses on the Consolidated Statements of Operations.
Payroll Tax Credit	Payroll Tax Credit In April 2019, we sold a portion of our French payroll tax credits earned in 2018 for net proceeds of $103.5 (€92.0). In April 2018, we sold substantially all of our French payroll tax credits earned in 2017 for net proceeds of $234.5 (€190.9). We derecognized these receivables and the additional interest upon the sale date as the terms of the agreement are such that the transaction qualifies for sale treatment in accordance with the accounting guidance on the transfer and servicing of assets. The discount on the sale of these receivables was recorded in cost of services as a reduction of the payroll tax credits.
Recently Issued Accounting Standards	(2) Recent Accounting Standards Accounting Standards Effective as of January 1, 2019 In February 2016, the Financial Accounting Standards Board ("FASB") issued new accounting guidance on leases, ASU No. 2016-02, Leases (Topic 842), which we adopted on January 1, 2019. The new guidance requires that a lessee recognize ROU assets and lease liabilities on the balance sheet for leases with lease terms longer than 12 months. The recognition, measurement and presentation of lease expenses and cash flows depend on the classification by the lessee as a finance or operating lease. We determined that no cumulative effect adjustment to retained earnings was necessary upon adoption. As of the transition date, the ROU asset and total lease liability (current and long-term) were $458.1 and $458.7, respectively. We elected the package of three practical expedients which lessened the transitional burden of implementing the new guidance. Accordingly, we did not reassess: 1) whether any expired or existing contracts are or contain leases; 2) the lease classification for any expired or existing leases; or 3) the initial direct costs for any existing leases. We have also elected the practical expedient to not separate lease and non-lease components. Lastly, we have elected to apply the short-term lease exception for all underlying asset classes. In August 2017, the FASB issued new guidance on hedge accounting. The amendments in this guidance include the elimination of the concept of recognizing periodic hedge ineffectiveness for cash flow and net investment hedges, recognition and presentation of changes in the fair value of the hedging instrument, recognition and presentation of components excluded from an entity's hedge effectiveness assessment, addition of the ability to elect to perform subsequent effectiveness assessments qualitatively, and addition of new disclosure requirements. We adopted this guidance effective January 1, 2019. There was no impact of this adoption on our Consolidated Financial Statements. See Note 13 to the Consolidated Financial Statements for the modified disclosures. In February 2018, the FASB issued new guidance on reporting comprehensive income. The new guidance allows a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the United States Tax Cuts and Jobs Act of 2017 ("Tax Act"). The guidance was effective for us as of January 1, 2019. We elected not to adopt this optional reclassification. In June 2018, the FASB issued new guidance on the accounting for share-based payment awards. The guidance makes the accounting for share-based payment awards issued to nonemployees largely consistent with the accounting for share-based payment awards issued to employees. We adopted this guidance effective January 1, 2019. There was no impact of this adoption on our Consolidated Financial Statements. Recently Issued Accounting Standards In June 2016, the FASB issued new accounting guidance on financial instruments. The new guidance requires application of an impairment model known as the current expected credit loss (“CECL”) model to certain financial instruments. Using the CECL model, an entity recognizes an allowance for expected credit losses based on historical experience, current conditions, and forecasted information rather than the current methodology of delaying recognition of credit losses until it is probable loss has been incurred. The new guidance is effective for us in 2020. We do not expect the adoption of this guidance to have a material impact on our Consolidated Financial Statements. In August 2018, the FASB issued new guidance on disclosures related to fair value measurements. The guidance is intended to improve the effectiveness of the notes to financial statements by facilitating clearer communication, and it includes multiple new, eliminated and modified disclosure requirements. The guidance is effective for us in 2020. The adoption of this guidance will have no impact on our Consolidated Financial Statements. In August 2018, the FASB issued new guidance on the accounting for internal-use software. The guidance aligns the accounting for costs incurred to implement a cloud computing arrangement that is a service arrangement with the guidance on capitalizing costs associated with developing or obtaining internal-use software. The guidance is effective for us in 2020. We are assessing the impact of the adoption of this guidance on our Consolidated Financial Statements. In August 2018, the FASB issued new guidance on disclosures related to defined benefit plans. The guidance amends the current disclosure requirements to add, remove and clarify disclosure requirements for defined benefit pension and other postretirement plans. The guidance is effective for us in 2020. The adoption of this guidance will have no impact on our Consolidated Financial Statements.

Basis of Presentation and Accounting Policies (Policies)

9 Months Ended

Sep. 30, 2019

Certain information and footnote disclosures normally included in the financial statements prepared in accordance with United States Generally Accepted Accounting Principles ("GAAP") have been condensed or omitted pursuant to the rules and regulations of the Securities and Exchange Commission, although we believe that the disclosures are adequate to make the information presented not misleading. These Consolidated Financial Statements should be read in conjunction with the Consolidated Financial Statements included in our 2018 Annual Report on Form 10-K.

The information furnished reflects all adjustments that, in the opinion of management, were necessary for a fair statement of the Consolidated Financial Statements for the periods presented. Such adjustments were of a normal recurring nature, unless otherwise disclosed.

Leases

We determine whether a contract is or contains a lease at contract inception. Right-of-use (“ROU”) assets and long-term lease liabilities are presented as separate line items on our Consolidated Balance Sheets. Current operating lease liabilities are included in accrued expenses on our Consolidated Balance Sheets.

ROU assets represent our right to use an underlying asset for the lease term and lease liabilities represent our obligation to make lease payments arising from the lease. Lease liabilities are recognized at commencement date based on the present value of remaining lease payments over the lease term. As the rate implicit in the lease is not readily determinable in most of our leases, we use our incremental borrowing rate. We determine our incremental borrowing rate at the commencement date using our unsecured borrowing rate, adjusted for collaterization, lease term, economic environment, currency and other factors. ROU assets are recognized at commencement date at the value of the related lease liabilities, adjusted for any prepayments, lease incentives received, and initial direct costs incurred. Our lease terms include options to renew or not terminate the lease when it is reasonably certain that we will exercise that option.

Lease expenses for operating leases are recognized on a straight-line basis over the lease term and recorded in selling and administrative expenses on the Consolidated Statements of Operations.

Payroll Tax Credit

In April 2019, we sold a portion of our French payroll tax credits earned in 2018 for net proceeds of $103.5 (€92.0). In April 2018, we sold substantially all of our French payroll tax credits earned in 2017 for net proceeds of $234.5 (€190.9). We derecognized these receivables and the additional interest upon the sale date as the terms of the agreement are such that the transaction qualifies for sale treatment in accordance with the accounting guidance on the transfer and servicing of assets. The discount on the sale of these receivables was recorded in cost of services as a reduction of the payroll tax credits.

Recently Issued Accounting Standards

(2) Recent Accounting Standards

Accounting Standards Effective as of January 1, 2019

In February 2016, the Financial Accounting Standards Board ("FASB") issued new accounting guidance on leases, ASU No. 2016-02, Leases (Topic 842), which we adopted on January 1, 2019. The new guidance requires that a lessee recognize ROU assets and lease liabilities on the balance sheet for leases with lease terms longer than 12 months. The recognition, measurement and presentation of lease expenses and cash flows depend on the classification by the lessee as a finance or operating lease. We determined that no cumulative effect adjustment to retained earnings was necessary upon adoption. As of the transition date, the ROU asset and total lease liability (current and long-term) were $458.1 and $458.7, respectively.

We elected the package of three practical expedients which lessened the transitional burden of implementing the new guidance. Accordingly, we did not reassess: 1) whether any expired or existing contracts are or contain leases; 2) the lease classification for any expired or existing leases; or 3) the initial direct costs for any existing leases. We have also elected the practical expedient to not separate lease and non-lease components. Lastly, we have elected to apply the short-term lease exception for all underlying asset classes.

In August 2017, the FASB issued new guidance on hedge accounting. The amendments in this guidance include the elimination of the concept of recognizing periodic hedge ineffectiveness for cash flow and net investment hedges, recognition and presentation of changes in the fair value of the hedging instrument, recognition and presentation of components excluded from an entity's hedge effectiveness assessment, addition of the ability to elect to perform subsequent effectiveness assessments qualitatively, and addition of new disclosure requirements. We adopted this guidance effective January 1, 2019. There was no impact of this adoption on our Consolidated Financial Statements. See Note 13 to the Consolidated Financial Statements for the modified disclosures.

In February 2018, the FASB issued new guidance on reporting comprehensive income. The new guidance allows a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the United States Tax Cuts and Jobs Act of 2017 ("Tax Act"). The guidance was effective for us as of January 1, 2019. We elected not to adopt this optional reclassification.

In June 2018, the FASB issued new guidance on the accounting for share-based payment awards. The guidance makes the accounting for share-based payment awards issued to nonemployees largely consistent with the accounting for share-based payment awards issued to employees. We adopted this guidance effective January 1, 2019. There was no impact of this adoption on our Consolidated Financial Statements.

Recently Issued Accounting Standards

In June 2016, the FASB issued new accounting guidance on financial instruments. The new guidance requires application of an impairment model known as the current expected credit loss (“CECL”) model to certain financial instruments. Using the CECL model, an entity recognizes an allowance for expected credit losses based on historical experience, current conditions, and forecasted information rather than the current methodology of delaying recognition of credit losses until it is probable loss has been incurred. The new guidance is effective for us in 2020. We do not expect the adoption of this guidance to have a material impact on our Consolidated Financial Statements.

In August 2018, the FASB issued new guidance on disclosures related to fair value measurements. The guidance is intended to improve the effectiveness of the notes to financial statements by facilitating clearer communication, and it includes multiple new, eliminated and modified disclosure requirements. The guidance is effective for us in 2020. The adoption of this guidance will have no impact on our Consolidated Financial Statements.

In August 2018, the FASB issued new guidance on the accounting for internal-use software. The guidance aligns the accounting for costs incurred to implement a cloud computing arrangement that is a service arrangement with the guidance on capitalizing costs associated with developing or obtaining internal-use software. The guidance is effective for us in 2020. We are assessing the impact of the adoption of this guidance on our Consolidated Financial Statements.

In August 2018, the FASB issued new guidance on disclosures related to defined benefit plans. The guidance amends the current disclosure requirements to add, remove and clarify disclosure requirements for defined benefit pension and other postretirement plans. The guidance is effective for us in 2020. The adoption of this guidance will have no impact on our Consolidated Financial Statements.