Unaudited Consolidated Statements of Cash Flows - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024
Cash flows from operating activities
Net income	$ 228.9	$ 315.2
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	81.9	68.1
Accretion of discount on available-for-sale securities	(4.9)	(0.1)
Non-cash marketing expense	0.8	0.8
Amortization of debt issuance costs	0.5	0.6
Stock-based compensation expense	60.6	(69.7)
Deferred income taxes, net	0.7	(7.8)
Other	0.5	(0.2)
Changes in operating assets and liabilities:
Accounts receivable	(0.7)	(3.6)
Prepaid expenses	(11.5)	(8.3)
Inventory	(0.2)	0.4
Other assets	(0.2)	(0.4)
Deferred contract costs	(45.4)	(55.2)
Income taxes, net	5.6	28.7
Accounts payable	(3.6)	0.0
Accrued commissions and bonuses	(6.7)	(8.3)
Accrued payroll and vacation	0.0	4.2
Deferred revenue	5.1	11.9
Accrued expenses and other current liabilities	(8.0)	3.9
Net change in operating right-of-use assets and operating lease liabilities	1.6	0.5
Net cash provided by operating activities	305.0	280.7
Cash flows from investing activities
Purchases of investments from funds held for clients	(465.8)
Proceeds from investments from funds held for clients		165.0
Purchases of property and equipment	(99.4)	(93.3)
Net cash (used in) provided by investing activities	(565.2)	71.7
Cash flows from financing activities
Repurchases of common stock		(80.8)
Withholding taxes paid related to net share settlements	(37.8)	(12.4)
Dividends paid	(42.9)	(42.4)
Net change in client funds obligation	(2,048.8)	(24.9)
Net cash (used in) provided by financing activities	(2,129.5)	(160.4)
(Decrease) increase in cash, cash equivalents, restricted cash and restricted cash equivalents	(2,389.7)	192.0
Cash, cash equivalents, restricted cash and restricted cash equivalents
Cash, cash equivalents, restricted cash and restricted cash equivalents, beginning of period	4,042.8	2,422.8
Cash, cash equivalents, restricted cash and restricted cash equivalents, end of period	1,653.1	2,614.7
Cash and cash equivalents	532.2	346.5
Restricted cash included in funds held for clients	1,120.9	2,268.3
Total cash, cash equivalents, restricted cash and restricted cash equivalents, end of period	1,653.1	2,614.7
Non-cash investing and financing activities:
Purchases of property and equipment, accrued but not paid	11.4	8.5
Stock-based compensation for capitalized software	13.7	8.8
Right of use assets obtained in exchange for operating lease liabilities	$ 5.3	$ 11.9