CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Cash Flows from Operating Activities
Net income	$ 49.5	$ 66.8
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	24.9	20.1
Stock-based compensation	12.1	12.8
Other	1.5	2.8
Changes in operating assets and liabilities, net of effects of acquisitions and divestiture:
Accounts receivable	31.0	(67.7)
Prepaid expenses and income taxes	16.5	23.1
Accounts payable	(1.2)	(0.5)
Accrued payroll	(33.8)	6.6
Other	(20.0)	(8.0)
Net cash provided by operating activities	80.5	56.0
Cash Flows from Investing Activities
Cash paid for property and equipment	(11.7)	(9.6)
Cash received from sale of the Oxford business	0.0	9.8
Other	(0.6)	0.0
Net cash provided by (used in) investing activities	(12.3)	0.2
Cash Flows from Financing Activities
Proceeds from long-term debt	36.0	0.0
Repayments of Long-term Debt	67.5	0.0
Proceeds from employee stock purchase plan	11.1	10.4
Repurchases of common stock	(48.8)	(76.9)
Payment of employment taxes related to release of restricted stock awards	(4.2)	(8.8)
Payment of contingent consideration	0.0	(8.1)
Net cash used in financing activities	(73.4)	(83.4)
Effect of exchange rate changes on cash and cash equivalents	(0.1)	0.0
Net decrease in cash and cash equivalents	(5.3)	(27.2)
Cash and cash equivalents at beginning of year	70.3	529.6
Cash and cash equivalents at end of period	65.0	502.4
Supplemental Disclosure of Cash Flow Information
Income taxes	2.0	1.9
Interest	8.6	2.4
Operating leases	6.6	6.9
Noncash transactions —
Operating lease right of use assets obtained in exchange for operating lease liabilities	$ 7.7	$ 2.5