CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Cash Flows from Operating Activities
Net income	$ 212.5	$ 324.9
Adjustments to reconcile net income to net cash provided by operating activities:
Discontinued Operation, Gain (Loss) from Disposal of Discontinued Operation, before Income Tax	0.0	(218.6)
Depreciation and amortization	64.8	67.5
Stock-based compensation	35.9	41.7
Deferred Income Taxes and Tax Credits	0.3	(42.4)
Other	6.5	3.7
Changes in operating assets and liabilities, net of effects of acquisitions and divestiture:
Accounts receivable	(154.2)	(99.5)
Prepaid expenses and income taxes	26.4	12.6
Accounts payable	10.0	(12.0)
Accrued payroll	20.0	75.3
Income taxes payable	15.1	130.6
Other	(4.8)	(7.9)
Net cash provided by operating activities	232.5	275.9
Cash Flows from Investing Activities
Cash paid for property and equipment	(27.0)	(25.6)
Cash paid for acquisitions, net of cash acquired	(351.8)	(224.4)
Cash received from sale of the Oxford business	9.8	499.1
Other	2.4	0.1
Net cash provided by (used in) investing activities	(366.6)	249.2
Cash Flows from Financing Activities
Proceeds from long-term debt	46.0	0.0
Proceeds from employee stock purchase plan	18.9	14.3
Repurchases of common stock	(227.6)	(118.4)
Payment of employment taxes related to release of restricted stock awards	(12.9)	(13.9)
Payment of contingent consideration	(8.1)	0.0
Debt issuance and amendment costs	0.0	(1.4)
Net cash used in financing activities	(183.7)	(119.4)
Effect of exchange rate changes on cash and cash equivalents	(0.6)	(0.7)
Net increase (decrease) in cash and cash equivalents	(318.4)	405.0
Cash and cash equivalents at beginning of year	529.6	274.4
Cash and cash equivalents at end of period	211.2	679.4
Supplemental Disclosure of Cash Flow Information
Income taxes	33.4	39.6
Interest	23.6	20.1
Operating leases	20.4	25.3
Noncash transactions —
Operating lease right of use assets obtained in exchange for operating lease liabilities	$ 15.5	$ 3.4