CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Cash flows from operating activities:
Net income	$ 235.5	$ 220.3
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization	41.4	31.1
Depreciation	9.9	8.1
Non-cash stock-based compensation	24.4	20.1
Change in estimated acquisition earn-out payables	(2.3)	(3.4)
Deferred income taxes	0.6	15.2
Amortization of debt discount and disposal of deferred financing costs	1.0	0.7
Net (gain)/loss on sales/disposals of investments, fixed assets and customer accounts	(5.4)	(0.1)
Payments on acquisition earn-outs in excess of original estimated payables		(13.5)
Effect of changes in foreign exchange rate changes		(0.1)
Changes in operating assets and liabilities, net of effect from acquisitions and divestitures:
Commissions, fees and other receivables (increase) decrease	(130.7)	(87.8)
Reinsurance recoverable (increase) decrease	688.3	24.8
Prepaid reinsurance premiums (increase) decrease	13.6	29.8
Other assets (increase) decrease	(6.1)	31.0
Losses and loss adjustment reserve increase (decrease)	(687.0)	(24.8)
Unearned premiums increase (decrease)	(12.7)	(29.7)
Accounts payable increase (decrease)	71.5	22.2
Accrued expenses and other liabilities increase (decrease)	(169.8)	(143.1)
Other liabilities increase (decrease)	(12.4)	2.8
Net cash provided by operating activities	59.8	103.6
Cash flows from investing activities:
Additions to fixed assets	(11.8)	(10.0)
Payments for businesses acquired, net of cash acquired	(37.6)	(436.0)
Proceeds from sales of fixed assets and customer accounts	6.1	0.2
Purchases of investments	(3.6)
Proceeds from sales of investments	3.7
Net cash used in investing activities	(43.2)	(445.8)
Cash flows from financing activities:
Fiduciary receivables and liabilities, net	(18.7)	(85.2)
Payments on acquisition earn-outs	(16.1)	(33.4)
Proceeds from long-term debt		1,200.0
Payments on long-term debt	(16.9)	(10.6)
Deferred debt issuance costs		(23.4)
Borrowings on revolving credit facility		350.0
Repurchase shares to fund tax withholdings for non-cash stock-based compensation	(36.2)	(46.0)
Purchase of treasury stock	(0.1)	(24.1)
Cash dividends paid	(32.6)	(28.9)
Net cash (used in)/provided by financing activities	(120.6)	1,298.4
Effect of foreign exchange rate changes on cash and cash equivalents inclusive of fiduciary cash	14.3	(0.3)
Net (decrease)/increase in cash and cash equivalents inclusive of fiduciary cash	(89.7)	955.9
Cash and cash equivalents inclusive of fiduciary cash at beginning of period	2,033.2	1,470.2
Cash and cash equivalents inclusive of fiduciary cash at end of period	$ 1,943.5	$ 2,426.1