CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Cash flows from operations:
Net income (loss)	$ 284.1	$ 580.9	$ 712.4
Adjustments to reconcile net income to net cash provided from (used for) operations:
Net realized and unrealized investment (gains) losses	(184.9)	(434.2)	191.5
Change in fair value of contingent consideration - Ark	61.3	48.7	17.3
Change in fair value of BAM Surplus Notes	(0.5)	0.0	0.0
Unrealized loss on deconsolidation of BAM	114.5	0.0	0.0
Deferred income tax expense (benefit)	11.1	(46.9)	12.9
Amortization of restricted share awards	16.3	15.3	14.0
Amortization (accretion) and depreciation	(6.4)	(17.8)	4.3
Net (income) loss from discontinued operation, net of tax - NSM Group	0.0	0.0	(16.4)
Other operating items:
Net change in reinsurance recoverables	(147.0)	153.3	(79.8)
Net change in insurance premiums, commissions and fees receivable	(204.7)	(67.0)	(127.8)
Net change in deferred acquisition costs	(27.1)	(22.2)	(21.9)
Net change in loss and loss adjustment expense reserves	543.0	308.6	401.8
Net change in unearned insurance premiums	174.4	147.9	159.3
Net change in reinsurance payable	68.4	(170.0)	(173.0)
Net change in premiums and commissions payable	38.9	0.0	0.0
Contributions to Kudu’s Participation Contracts	(103.5)	(163.8)	(99.8)
Proceeds from Kudu’s Participation Contracts sold	9.4	75.2	137.5
Net other operating activities	(50.5)	(3.9)	80.8
Net cash provided from (used for) operations - continuing operations	586.8	404.1	326.3
Net cash provided from (used for) operations - NSM Group discontinued operations (Note 20)	0.0	0.0	38.7
Net cash provided from (used for) operations	586.8	404.1	365.0
Cash flows from investing activities:
Net change in short-term investments	548.4	(495.8)	(455.1)
Sales of fixed maturity investments	429.5	195.1	188.7
Maturities, calls and paydowns of fixed maturity investments	416.5	266.5	198.5
Sales of common equity securities and investment in MediaAlpha	162.4	261.6	0.0
Distributions and redemptions of other long-term investments	195.7	116.9	115.4
Proceeds from the sale of NSM Group and Other Operating Businesses, net of cash sold of $0.0, $0.8 and $144.4	0.0	17.3	1,392.0
Purchases of consolidated subsidiaries, net of cash acquired of $44.9, $0.0, and $0.3	(231.8)	0.0	(67.9)
Release of cash (pre-funding) for ILS funds managed by Elementum	0.0	70.0	(70.0)
Purchases of fixed maturity investments	(1,677.5)	(592.7)	(585.5)
Purchases of common equity securities and investment in MediaAlpha	(121.1)	(114.2)	(424.5)
Purchases of other long-term investments	(190.2)	(265.2)	(178.8)
Payments of principal received on the BAM Surplus Notes subsequent to deconsolidation	16.2	0.0	0.0
Impact to cash from deconsolidation of BAM	(4.2)	0.0	0.0
Net other investing activities	9.1	(3.4)	(4.4)
Net cash provided from (used for) investing activities - continuing operations	(447.0)	(543.9)	108.4
Net cash provided from (used for) investing activities - NSM Group discontinued operations (Note 20)	0.0	0.0	7.1
Net cash provided from (used for) investing activities	(447.0)	(543.9)	115.5
Cash flows from financing activities:
Draw down of debt and revolving lines of credit	36.6	12.4	213.8
Repayment of debt and revolving lines of credit	(38.1)	(25.7)	(56.7)
Cash dividends paid to common shareholders	(2.5)	(2.6)	(3.0)
Repurchases and retirements of common shares	(7.9)	(32.7)	(615.8)
BAM member surplus contributions prior to deconsolidation	26.0	72.8	81.4
Contributions from other noncontrolling interests	1.0	9.0	74.6
Distributions to other noncontrolling interests	(21.1)	(12.0)	(21.6)
Net (contributions to) distributions from discontinued operations	0.0	0.0	11.6
Net other financing activities	10.2	(14.0)	(11.7)
Net cash provided from (used for) financing activities - continuing operations	4.2	7.2	(327.4)
Net cash provided from (used for) financing activities - NSM Group discontinued operations (Note 20)	0.0	0.0	(17.5)
Net cash provided from (used for) financing activities	4.2	7.2	(344.9)
Net change in cash during the period - continuing operations	144.0	(132.6)	107.3
Cash balance at beginning of year	122.4	255.0	147.7
Cash balance at end of year	266.4	122.4	255.0
Operating Segments | Financial Guarantee (HG Global)
Adjustments to reconcile net income to net cash provided from (used for) operations:
Net realized and unrealized investment (gains) losses	11.5	(26.6)	105.8
Interest income from BAM Surplus Notes subsequent to deconsolidation, net of interest payments received of $5.8	(10.0)	0.0	0.0
Change in fair value of BAM Surplus Notes	(0.5)	0.0	0.0
Unrealized loss on deconsolidation of BAM	114.5	0.0	0.0
NSM
Adjustments to reconcile net income to net cash provided from (used for) operations:
Net (income) loss from discontinued operation, net of tax - NSM Group	0.0	0.0	(16.4)
Net (gain) loss from sale of discontinued operations, net of tax - NSM Group	0.0	0.0	(886.8)
Investments, Excluding MediaAlpha
Adjustments to reconcile net income to net cash provided from (used for) operations:
Net realized and unrealized investment (gains) losses	(146.9)	(407.1)	98.5
MediaAlpha
Adjustments to reconcile net income to net cash provided from (used for) operations:
Net realized and unrealized investment (gains) losses	$ (38.0)	$ (27.1)	$ 93.0