Unaudited Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Cash flows from operating activities
Net income	$ 119,296	$ 91,930
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	26,272	21,655
Accretion of discount on available-for-sale securities	(124)	(303)
Non-cash marketing expense	418	437
Gain on disposition of property and equipment	(13)
Amortization of debt issuance costs	308	9
Stock-based compensation expense	27,819	22,055
Cash paid for derivative settlement		(174)
Gain on derivative		(1,089)
Deferred income taxes, net	(1,650)	(10,332)
Other	78
Changes in operating assets and liabilities:
Accounts receivable	5,041	(8,455)
Prepaid expenses	(6,984)	(4,859)
Inventory	385	124
Other assets	2,923	(2,970)
Deferred contract costs	(38,519)	(36,261)
Accounts payable	(4,645)	5,406
Income taxes, net	24,933	39,593
Accrued commissions and bonuses	(10,845)	(10,309)
Accrued payroll and vacation	(8,835)	8,579
Deferred revenue	3,386	3,390
Accrued expenses and other current liabilities	6,859	(1,195)
Net cash provided by operating activities	146,103	117,231
Cash flows from investing activities
Purchases of investments from funds held for clients	(25,000)	(169,152)
Proceeds from investments from funds held for clients	25,000	136,000
Purchases of property and equipment	(40,618)	(34,474)
Net cash used in investing activities	(40,618)	(67,626)
Cash flows from financing activities
Withholding taxes paid related to net share settlements	(626)	(218)
Payments on long-term debt		(444)
Net change in client funds obligation	183,629	2,099,530
Net cash provided by (used in) financing activities	183,003	2,098,868
Increase (decrease) in cash, cash equivalents, restricted cash and restricted cash equivalents	288,488	2,148,473
Cash, cash equivalents, restricted cash and restricted cash equivalents
Cash, cash equivalents, restricted cash and restricted cash equivalents, beginning of period	2,409,095	1,812,691
Cash, cash equivalents, restricted cash and restricted cash equivalents, end of period	2,697,583	3,961,164
Cash and cash equivalents	505,590	360,594
Restricted cash included in funds held for clients	2,191,993	3,600,570
Total cash, cash equivalents, restricted cash and restricted cash equivalents, end of period	2,697,583	3,961,164
Non-cash investing and financing activities:
Purchases of property and equipment, accrued but not paid	6,991	5,394
Stock-based compensation for capitalized software	3,597	1,891
Right of use assets obtained in exchange for operating lease liabilities	$ 1,933	$ 4,146