Consolidated Statements of Cash Flows - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 92,400,000	$ 2,600,000
Adjustments to reconcile net income to net cash used in operating activities:
Depreciation and amortization	69,200,000	72,800,000
Loss on Extinguishment of Debt	74,000,000.0	(0.0)
Amortization of restricted stock and other non-cash compensation	20,300,000	23,200,000
Deferred income tax	18,200,000	(11,200,000)
Net losses on sales of businesses	12,500,000	23,300,000
Net amortization of bond discounts and deferred financing costs	2,700,000	2,300,000
(Reversal of) Provision for uncollectible receivables	(2,200,000)	22,600,000
Other	4,600,000	1,200,000
Changes in assets and liabilities, net of acquisitions and divestitures, providing (using) cash:
Accounts receivable	1,158,600,000	1,343,500,000
Accounts receivable, billable to clients	40,800,000	40,700,000
Other current assets	(68,800,000)	(57,500,000)
Accounts payable	(1,347,000,000.0)	(1,466,900,000)
Accrued liabilities	(233,600,000)	(158,800,000)
Contract liabilities	34,700,000	8,800,000
Other non-current assets and liabilities	(44,600,000)	(42,300,000)
Net cash used in operating activities	(249,800,000)	(277,100,000)
CASH FLOWS FROM INVESTING ACTIVITIES:
Capital expenditures	(28,300,000)	(44,600,000)
Acquisitions, net of cash acquired	0.0	(1,300,000)
Net proceeds from investments	(28,800,000)	(1,800,000)
Other investing activities	(300,000)	(16,700,000)
Net cash provided by (used in) investing activities	200,000	(60,800,000)
CASH FLOWS FROM FINANCING ACTIVITIES:
Early extinguishment of long-term debt	(1,066,800,000)	0.0
Common stock dividends	(109,100,000)	(100,000,000.0)
Tax payments for employee shares withheld	(22,400,000)	(19,100,000)
Acquisition-related payments	(3,400,000)	(18,600,000)
Distributions to noncontrolling interests	(3,300,000)	(5,600,000)
Net (decrease) increase in short-term borrowings	(2,900,000)	247,800,000
Proceeds from Issuance of Long-term Debt	998,100,000	646,200,000
Exercise of stock options	8,000,000.0	0.0
Other financing activities	(10,900,000)	(6,300,000)
Net cash (used in) provided by financing activities	(212,700,000)	744,400,000
Effect of foreign exchange rate changes on cash, cash equivalents and restricted cash	(30,400,000)	(46,700,000)
Net (decrease) increase in cash, cash equivalents and restricted cash	(492,700,000)	359,800,000
Cash, cash equivalents, and restricted cash at beginning of period	2,511,500,000	1,195,700,000
Cash, cash equivalents, and restricted cash at end of period	$ 2,018,800,000	$ 1,555,500,000