CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Operating activities
Net income	$ 307	$ 269
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	72	63
Amortization of ROU asset, lease modification and impairment	15	10
Stock based compensation	46	37
Deferred income taxes	1	0
Provision for doubtful accounts	1	0
Loss from sales and impairments of investments	18	0
Loss from dispositions of assets	3	0
Other	2	4
Changes in operating assets and liabilities:
Accounts receivable, net	10	10
Unbilled revenue, net	(38)	(59)
Other assets and prepaid expenses, net	(83)	(44)
Accounts payable and other liabilities	5	16
Client deposits and other client liabilities	(43)	(14)
Accrued wages	40	246
Accrued health insurance costs, net	(10)	(10)
Accrued workers' compensation costs, net	(5)	(6)
Payroll taxes payable and other payroll withholdings	(252)	(528)
Operating lease liabilities	(13)	(10)
Net cash provided by (used in) operating activities	76	(16)
Investing activities
Purchases of marketable securities	(337)	(348)
Proceeds from sale and maturity of marketable securities	390	232
Purchases of property and equipment	(39)	(29)
Acquisition of subsidiaries, net of cash acquired	(219)	0
Net cash used in investing activities	(205)	(145)
Financing activities
Repurchase of common stock	(383)	(94)
Proceeds from issuance of common stock	6	6
Awards effectively repurchased for required employee withholding taxes	(15)	(13)
Payment of long-term financing fees and debt issuance costs	0	(9)
Proceeds from issuance of 2029 Notes	0	500
Repayment of debt	0	(370)
Net cash provided by (used in) financing activities	(392)	20
Net decrease in cash and cash equivalents, unrestricted and restricted	(521)	(141)
Cash and cash equivalents, unrestricted and restricted:
Beginning of period	1,738	1,643
End of period	1,217	1,502
Supplemental disclosures of cash flow information
Interest paid	18	11
Income taxes (refund) paid, net	60	83
Supplemental schedule of noncash investing and financing activities
Payable for purchase of property and equipment	7	3
Payable for acquisition of subsidiaries	$ 4	$ 0