Condensed Consolidated Balance Sheets - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 253.7	$ 209.3
Funds receivable and funds held on behalf of clients	2,030.0	1,227.4
Accounts receivable, net of allowance for doubtful accounts of $16.9 and $16.8, respectively	674.5	648.0
Contract asset	27.2	20.4
Prepaid expenses and other current assets	209.4	187.5
Restricted cash and cash equivalents	4.4	5.9
Total current assets	3,199.2	2,298.5
Property, plant and equipment, net (Note 2)	402.7	412.8
Operating lease right-of-use assets	339.2	350.8
Investments (Note 3)	193.6	183.5
Unconsolidated affiliates (Note 4)	228.5	225.6
Contract asset	81.7	82.0
Goodwill (Note 6)	8,078.1	8,078.7
Intangible and other assets, net of accumulated amortization of $2,802.4 and $2,655.6, respectively	4,166.1	4,291.7
Total assets	16,689.1	15,923.6
Current liabilities:
Current portion of long-term debt (Note 7)	178.2	53.9
Client funds obligations	2,030.0	1,227.4
Accounts payable	27.9	28.1
Income taxes payable	46.8	9.3
Accrued employee compensation and benefits	177.5	311.5
Interest payable		27.5
Other accrued expenses	323.0	293.1
Deferred revenues	349.9	332.5
Total current liabilities	3,133.3	2,283.3
Long-term debt, net of current portion (Note 7)	6,338.1	6,388.5
Operating lease liabilities	311.8	323.6
Other long-term liabilities	280.9	287.9
Deferred income taxes	890.8	923.8
Total liabilities	10,954.9	10,207.1
Commitments and contingencies (Note 13)
Stockholders’ equity (Note 8):
Preferred stock, $0.01 par value per share, 5.0 million shares authorized; no shares issued
Common stock	2.6	2.6
Additional paid-in capital	4,600.5	4,544.0
Accumulated other comprehensive loss	(192.1)	(201.0)
Retained earnings	1,800.7	1,667.0
Stockholders' equity before treasury stock	6,211.7	6,012.6
Less: cost of common stock in treasury, 9.0 and 6.3 million shares, respectively	(477.5)	(296.1)
Total stockholders’ equity	5,734.2	5,716.5
Total liabilities and stockholders’ equity	16,689.1	15,923.6
Class A Non-Voting Common Stock [Member]
Stockholders’ equity (Note 8):
Common stock