CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Cash flows from operating activities:
Net income before non-controlling interests	$ 1,067	$ 1,002	$ 871
Adjustments to reconcile net income before non-controlling interests to net cash provided by operating activities:
Amortization	312	178	166
Depreciation	55	44	40
Non-cash stock-based compensation	93	101	89
Change in estimated acquisition earn-out payables	25	2	21
Mark-to-market of escrow liability	(54)	0	0
Deferred income taxes	(7)	13	12
Net loss/(gain) on sales/disposals of investments, businesses, fixed assets and customer accounts	3	(29)	(140)
Payments on acquisition earn-outs in excess of original estimated payables	(3)	(37)	(29)
Other	6	5	5
Changes in operating assets and liabilities, net of effect from acquisitions and divestitures:
Commissions, fees and other receivables (increase) decrease	(95)	(94)	(106)
Reinsurance recoverable (increase) decrease	1,356	(1,402)	706
Prepaid reinsurance premiums (increase) decrease	(182)	(58)	(68)
Other assets (increase) decrease	(44)	(98)	(117)
Losses and loss adjustment reserve increase (decrease)	(1,348)	1,411	(710)
Unearned premiums increase (decrease)	177	115	50
Accounts payable increase (decrease)	11	(47)	260
Accrued expenses and other liabilities increase (decrease)	18	35	43
Other liabilities increase (decrease)	60	33	(83)
Net cash provided by operating activities	1,450	1,174	1,010
Cash flows from investing activities:
Additions to fixed assets	(68)	(82)	(69)
Payments for businesses acquired, net of cash acquired	(7,854)	(890)	(631)
Proceeds from sales of businesses, fixed assets and customer accounts	9	70	107
Other investing activities	(1)	4	6
Net cash used in investing activities	(7,914)	(898)	(587)
Cash flows from financing activities:
Fiduciary receivables and liabilities, net	53	191	189
Payments on acquisition earn-outs	(143)	(117)	(90)
Proceeds from long-term debt	4,192	599	0
Payments on long-term debt	(225)	(719)	(251)
Deferred debt issuance costs	(36)	(5)	0
Borrowings on revolving credit facility	450	500	420
Payments on revolving credit facility	(600)	(350)	(320)
Proceeds from issuance of common stock, net of expenses	4,315	0	0
Issuances of common stock for employee stock benefit plans	48	44	40
Repurchase shares to fund tax withholdings for non-cash stock-based compensation	(42)	(55)	(40)
Purchase of treasury stock	(100)	0	0
Cash dividends paid	(193)	(154)	(135)
Other financing activities	(6)	2	0
Net cash provided by (used in) financing activities	7,713	(64)	(187)
Effect of foreign exchange rate changes on cash, cash equivalents and restricted cash inclusive of fiduciary cash	64	(13)	34
Net increase in cash, cash equivalents and restricted cash inclusive of fiduciary cash	1,313	199	270
Cash, cash equivalents and restricted cash inclusive of fiduciary cash at beginning of period	2,502	2,303	2,033
Cash, cash equivalents and restricted cash inclusive of fiduciary cash at end of period	$ 3,815	$ 2,502	$ 2,303