CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Cash flows provided by (used in) operating activities:
Net income (loss)	$ (94.0)	$ (78.5)
Adjustments to reconcile net income (loss) to cash provided by operating activities:
Amortization and depreciation	138.3	11.3
Share-based payments expense	0.0	0.3
Deferred income tax expense (benefit), net	(26.5)	4.7
Net investment and other (gains) losses	(30.8)	21.0
Undistributed earnings from alternative investment portfolio	(16.9)	(9.3)
Foreign currency exchange (gains) losses	(3.1)	0.1
Change in:
Accrued investment income	0.6	(1.6)
Receivables	(132.4)	743.4
Deferred acquisition costs	(44.5)	(10.7)
Ceded unearned premiums	(28.8)	(19.5)
Reserves for losses and loss adjustment expenses	232.1	(223.8)
Unearned premiums	(77.2)	(10.6)
Ceded reinsurance payable and funds held	6.3	(55.8)
Income taxes	30.5	(1.7)
Accrued underwriting expenses and other liabilities	33.4	(46.6)
Other, net	(70.6)	(51.2)
Cash (used in) provided by operating activities	(83.6)	271.5
Cash flows provided by (used in) investing activities:
Sales of fixed maturity investments	110.3	21.4
Maturities and mandatory calls of fixed maturity investments	398.4	119.5
Sales of equity securities	2.8	45.7
Sales of other investments	68.9	21.5
Purchases of fixed maturity investments	(224.0)	(11.9)
Purchases of equity securities	(48.6)	(0.3)
Purchases of other investments	(171.3)	(16.6)
Change in short-term investments	(200.3)	(566.4)
Settlements of foreign currency exchange forward contracts	0.8	4.5
Proceeds from business divestitures, net of cash transferred	0.0	62.9
Purchases of fixed assets, net	0.0	(2.4)
Cash used in investing activities	(342.1)	(322.1)
Cash flows provided by (used in) financing activities:
Debt borrowings	100.0	0.0
Repayment of debt	(100.0)	0.0
Issuance of common stock	200.0	0.0
Activity under stock incentive plans	0.0	1.2
Payment of cash dividends to preferred stockholders	(7.9)	(7.9)
Payment of cash dividends to common stockholders	0.0	0.2
Cash provided by (used in) financing activities	192.1	(6.5)
Effect of exchange rate changes on cash	0.0	0.3
Net change in cash and restricted cash including balances classified as held-for-sale	(233.6)	(56.8)
Net change in cash balances classified as held-for-sale	0.0	70.8
Cash, restricted cash, and cash equivalents, beginning of period	791.6	50.2
Cash, restricted cash, and cash equivalents, end of period	558.0	64.2
Mortgage Loans
Cash flows provided by (used in) investing activities:
Proceeds from loans	19.9	0.0
Purchase of loans	(108.3)	0.0
Private Loans
Cash flows provided by (used in) investing activities:
Proceeds from loans	15.3	0.0
Purchase of loans	$ (206.0)	$ 0.0