CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Cash Flows from Operating Activities
Net income	$ 109.6	$ 139.3
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	49.8	39.8
Stock-based compensation	23.4	24.0
Other	3.4	5.1
Changes in operating assets and liabilities, net of effects of acquisitions and divestiture:
Accounts receivable	24.7	(136.7)
Prepaid expenses and income taxes	6.8	23.7
Accounts payable	(10.4)	12.1
Accrued payroll	(19.3)	31.9
Income taxes payable	16.1	8.0
Other	(11.1)	(2.8)
Net cash provided by operating activities	193.0	144.4
Cash Flows from Investing Activities
Cash paid for property and equipment	(22.9)	(18.4)
Cash received from the sale of a business	0.0	9.8
Other	(0.6)	2.5
Net cash used in investing activities	(23.5)	(6.1)
Cash Flows from Financing Activities
Proceeds from long-term debt	73.0	0.0
Repayments of Long-term Debt	104.5	0.0
Proceeds from employee stock purchase plan	11.1	10.4
Repurchases of common stock	(106.4)	(168.1)
Payment of employment taxes related to release of restricted stock awards	(14.2)	(11.3)
Payment of contingent consideration	(5.0)	(8.1)
Net cash used in financing activities	(146.0)	(177.1)
Effect of exchange rate changes on cash and cash equivalents	0.0	(0.2)
Net increase (decrease) in cash and cash equivalents	23.5	(39.0)
Cash and cash equivalents at beginning of year	70.3	529.6
Cash and cash equivalents at end of period	93.8	490.6
Supplemental Disclosure of Cash Flow Information
Income taxes	8.0	17.7
Interest	30.1	18.4
Operating leases	13.2	13.6
Noncash transactions —
Operating lease right of use assets obtained in exchange for operating lease liabilities	$ 13.9	$ 9.8