Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities
Net income (loss)	$ 0.2	$ (185.8)	$ (221.3)
Reconciliation of net income (loss) to net cash used in operating activities:
Depreciation and amortization	296.7	290.0	270.6
Impairment charges	12.2	2.7	0.0
Unrealized foreign exchange loss (gain)	(3.2)	8.4	(7.3)
Stock-based compensation	61.3	81.9	52.4
Loss on debt extinguishment	0.0	50.4	0.0
Lease amortization	117.9	0.0	0.0
Amortization of debt issuance costs	4.4	12.5	16.5
Gain on pension curtailment	0.0	0.0	(10.0)
Change in deferred taxes	(49.8)	(58.9)	(170.3)
Bad debt expense	22.1	21.7	3.9
Other non-cash operating activities	(16.8)	(3.6)	7.0
Changes in assets and liabilities:
Trade and other receivables	(38.9)	(235.5)	(173.4)
Income taxes payable	27.0	(19.6)	10.1
Prepaid expenses and other current assets	(154.9)	(26.9)	(17.6)
Other non-current assets	32.4	84.6	44.0
Accounts payable and accrued expenses	60.0	74.9	42.6
Accrued compensation	63.5	117.8	98.4
Other current and non-current liabilities	(164.8)	(216.8)	58.8
Net cash provided by (used in) operating activities	269.3	(2.2)	4.4
Cash flows from investing activities
Payment for property and equipment	(80.3)	(84.2)	(129.1)
Acquisitions of businesses, net of cash acquired	(275.9)	(35.5)	(99.9)
Investments in equity securities	(4.5)	(8.7)	0.0
Return of beneficial interest in a securitization	0.0	(85.0)	0.0
Collection on beneficial interest in a securitization	85.0	0.0	84.8
Other investing activities, net	0.8	(4.6)	1.0
Net cash used in investing activities	(274.9)	(218.0)	(143.2)
Cash flows from financing activities
Net proceeds from issuance of shares	0.3	9.0	23.4
Shares repurchased for payment of employee taxes on stock awards	(31.8)	(15.2)	(4.5)
Payment of contingent consideration	(17.3)	(22.3)	(8.4)
Proceeds from long-term borrowings	0.0	2,936.5	318.7
Repayment of borrowings	(27.0)	(3,133.2)	(150.3)
Debt issuance costs	0.0	(24.4)	(4.4)
Proceeds from initial public offering, net of underwriting	0.0	831.4	0.0
Proceeds from private placement	0.0	179.5	0.0
Payments of initial offering and private placement costs	0.0	(17.3)	0.0
Payment of finance lease liabilities	(11.5)	(10.8)	(9.1)
Other financing activities, net	(2.3)	(7.3)	2.3
Net cash (used in) provided by financing activities	(89.6)	725.9	167.7
Change in cash, cash equivalents and restricted cash	(95.2)	505.7	28.9
Cash, cash equivalents and restricted cash, beginning of the year	965.4	467.9	424.8
Effects of exchange rate fluctuations on cash, cash equivalents and restricted cash	2.1	(8.2)	14.2
Cash, cash equivalents and restricted cash, end of the year	$ 872.3	$ 965.4	$ 467.9