CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Operating activities
Net income	$ 146	$ 101
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	21	19
Stock based compensation	12	11
Amortization of ROU asset, lease modification and impairment	3	3
Deferred income taxes	2	0
Other	2	2
Changes in operating assets and liabilities:
Accounts receivable, net	8	13
Unbilled revenue, net	7	(94)
Other assets and prepaid expenses, net	(11)	(19)
Accounts payable and other liabilities	10	29
Client deposits and other client liabilities	28	17
Accrued wages	188	179
Accrued health insurance costs, net	(8)	(7)
Accrued workers' compensation costs, net	1	0
Payroll taxes payable and other payroll withholdings	(191)	(426)
Operating lease liabilities	(4)	(3)
Net cash provided by (used in) operating activities	214	(175)
Investing activities
Purchases of marketable securities	(91)	(82)
Proceeds from sale and maturity of marketable securities	72	84
Purchases of property and equipment	(11)	(5)
Acquisition of Zenefits, net of cash acquired	(183)	0
Net cash used in investing activities	(213)	(3)
Financing activities
Repurchase of common stock	(350)	(60)
Awards effectively repurchased for required employee withholding taxes	(3)	(5)
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	(353)	56
Net decrease in cash and cash equivalents, unrestricted and restricted	(352)	(122)
Cash and cash equivalents, unrestricted and restricted:
Beginning of period	1,738	1,643
End of period	1,386	1,521
Supplemental disclosures of cash flow information
Interest paid	9	2
Income taxes (refund) paid, net	$ (12)	$ 2