CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Operating activities
Net income	$ 214	$ 230
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of intangible assets	36	29
Amortization of deferred costs	20	18
Amortization of ROU asset, lease modification, impairment, and abandonment	2	6
Stock based compensation	28	30
Other	2	2
Changes in operating assets and liabilities:
Accounts receivable, net	(1)	8
Unbilled revenue, net	12	16
Other assets and prepaid expenses, net	(24)	(17)
Other payroll assets	68	(4)
Accounts payable and other liabilities	0	2
Client deposits and other client liabilities	(27)	(23)
Accrued wages	0	196
Accrued health insurance costs, net	(5)	(23)
Accrued workers' compensation costs, net	(9)	(9)
Payroll taxes payable and other payroll withholdings	(241)	(328)
Operating lease liabilities	(8)	(8)
Net cash provided by operating activities	67	125
Investing activities
Purchases of marketable securities	(170)	(157)
Proceeds from sale and maturity of marketable securities	173	175
Acquisitions of property and equipment	(34)	(26)
Acquisition of subsidiary, net of cash acquired	0	(183)
Net cash used in investing activities	(31)	(191)
Financing activities
Repurchase of common stock	(98)	(382)
Proceeds from issuance of common stock	7	5
Revolver drawdown	495	0
Revolver repayment	(495)	0
Awards effectively repurchased for required employee withholding taxes	(9)	(8)
Net cash used in financing activities	(100)	(385)
Net decrease in cash and cash equivalents, unrestricted and restricted	(64)	(451)
Cash and cash equivalents, unrestricted and restricted:
Beginning of period	1,537	1,738
End of period	1,473	1,287
Supplemental disclosures of cash flow information
Interest paid	12	9
Income taxes paid, net	58	37
Supplemental schedule of noncash investing and financing activities
Payable for purchase of property and equipment	$ 5	$ 3