CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 205,400,000	$ 357,400,000
Adjustments to reconcile net income to net cash used in operating activities:
Deferred income tax	(101,300,000)	(24,900,000)
Net amortization of bond discounts and deferred financing costs	300,000	900,000
Goodwill, Impairment Loss	0	232,100,000
Provision for uncollectible receivables	6,900,000	8,400,000
Amortization of restricted stock and other non-cash compensation	45,500,000	52,400,000
Net losses on sales of businesses	30,000,000.0	6,400,000
Depreciation and amortization	184,200,000	195,500,000
Restructuring charges	179,800,000	1,400,000
Other	33,500,000	33,500,000
Changes in assets and liabilities, net of acquisitions and divestitures, providing (using) cash:
Accounts receivable	852,600,000	958,900,000
Accounts receivable, billable to clients	13,100,000	(19,500,000)
Prepaid expenses	(70,000,000.0)	(58,700,000)
Other current assets	(3,700,000)	22,500,000
Accounts payable	(1,329,000,000)	(1,223,700,000)
Accrued liabilities	(9,400,000)	(183,600,000)
Contract liabilities	93,600,000	(115,000,000.0)
Other non-current assets and liabilities	(84,400,000)	(56,900,000)
Net cash provided by operating activities	47,100,000	187,100,000
CASH FLOWS FROM INVESTING ACTIVITIES:
Acquisitions, net of cash acquired	(48,400,000)	0
Capital expenditures	(73,800,000)	(107,200,000)
Net proceeds from investments	0	2,300,000
Net proceeds from sale of businesses, net of cash sold	8,100,000	(31,400,000)
Other investing activities	8,300,000	4,500,000
Net cash used in investing activities	(105,800,000)	(131,800,000)
CASH FLOWS FROM FINANCING ACTIVITIES:
Common stock dividends	(366,600,000)	(373,700,000)
Repurchases of common stock	(257,400,000)	(230,100,000)
Distributions to non-controlling interests	(28,000,000.0)	(13,700,000)
Tax payments for employee shares withheld	(16,100,000)	(13,900,000)
Acquisition-related payments	(21,500,000)	(8,700,000)
Repayment of long-term debt	(100,000)	(250,100,000)
Net increase (decrease) in short-term borrowings	15,400,000	(5,700,000)
Other financing activities	200,000	(1,700,000)
Net cash used in financing activities	(674,100,000)	(897,600,000)
Effect of foreign exchange rate changes on cash, cash equivalents and restricted cash	77,100,000	(11,100,000)
Net decrease in cash, cash equivalents and restricted cash	(655,700,000)	(853,400,000)
Cash, cash equivalents and restricted cash at beginning of period	2,196,400,000	2,395,100,000
Cash, cash equivalents and restricted cash at end of period	$ 1,540,700,000	$ 1,541,700,000