Supplementary Data Accrued Liabilities (Details) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Accrued Liabilities [Abstract]
Salaries, benefits and related expenses	$ 344.3	$ 507.5
Income Taxes payable	10.4	56.8
Interest	36.7	40.2
Office and related expenses	18.7	22.3
Acquisition obligations	7.6	2.9
Restructuring charges	0.3	0.6
Other	70.1	75.5
Total Accrued Liabilities	$ 488.1	$ 705.8

Acquisition related costs such as deferred payments and other obligations

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- Definition

Current office and related expenses such as deferred rent expense and lease costs.

+ References

No definition available.

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- Definition

Carrying amount as of the balance sheet date of the unpaid sum of the known and estimated amounts payable to satisfy all domestic and foreign income tax obligations due. This amount is the total of current and noncurrent accrued income taxes.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
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-Subparagraph (SX 210.5-02(20))
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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- Definition

Carrying value as of the balance sheet date of obligations incurred and payable, pertaining to costs that are statutory in nature, are incurred on contractual obligations, or accumulate over time and for which invoices have not yet been received or will not be rendered. Examples include taxes, interest, rent and utilities.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- References

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- Definition

Total of the carrying values as of the balance sheet date of obligations incurred through that date and payable for obligations related to services received from employees, such as accrued salaries and bonuses, payroll taxes and fringe benefits. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

+ References

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- Definition

Carrying value as of the balance sheet date of [accrued] interest payable on all forms of debt, including trade payables, that has been incurred and is unpaid. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

+ References

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- Definition

Amount of expenses incurred but not yet paid classified as other, due within one year or the normal operating cycle, if longer.

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- Definition

Carrying amount as of the balance sheet date of known and estimated obligations associated with exit from or disposal of business activities or restructurings pursuant to a duly authorized plan, which are expected to be paid in the next twelve months or in the normal operating cycle if longer. Costs of such activities include those for one-time termination benefits, termination of an operating lease or other contract, consolidating or closing facilities, relocating employees, and costs associated with an ongoing benefit arrangement, but excludes costs associated with the retirement of a long-lived asset.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 210
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-Name Accounting Standards Codification
-Section S99
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