Unaudited Condensed Consolidated Statements Of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
CASH FLOWS PROVIDED BY OPERATING ACTIVITIES:
Net income	$ 74.1	$ 124.4
Adjustments to reconcile net income to cash provided by operating activities:
Net realized gains on sales of investments	(12.0)	(32.5)
Mark to market adjustments	(27.1)	(22.7)
Stock compensation expense	3.9	4.0
Undistributed income of equity method investments	9.2	9.8
Changes in:
Reserve for losses and loss expenses, net of reinsurance recoverables	86.9	13.9
Unearned premiums, net of prepaid reinsurance	125.5	204.0
Insurance balances receivable	(139.5)	(108.6)
Reinsurance recoverable on paid losses	13.8	(21.0)
Funds held	287.7	244.1
Reinsurance balances payable	7.3	4.3
Net deferred acquisition costs	(21.7)	(35.7)
Net deferred tax assets	(0.6)	3.7
Accounts payable and accrued liabilities	(50.1)	(75.0)
Other items, net	(9.9)	5.0
Net cash provided by operating activities	347.5	317.7
CASH FLOWS USED IN INVESTING ACTIVITIES:
Purchases of trading securities	(1,530.0)	(1,723.4)
Purchases of other invested assets	(8.1)	(233.3)
Sales of trading securities	1,414.6	1,561.9
Sales of other invested assets	38.7	56.5
Purchases of fixed assets	(0.6)	(8.4)
Net cash paid on acquisition	0.0	(3.5)
Change in restricted cash	(26.8)	31.0
Net cash used in investing activities	(112.2)	(319.2)
CASH FLOWS USED IN FINANCING ACTIVITIES:
Dividends paid	(23.4)	(21.7)
Proceeds from the exercise of stock options	0.4	4.2
Repayment of other long-term debt	(0.1)	0.0
Share repurchases	(50.0)	(50.3)
Net cash used in financing activities	(73.1)	(67.8)
Effect of exchange rate changes on foreign currency cash	1.8	(5.0)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	164.0	(74.3)
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	608.0	589.3
CASH AND CASH EQUIVALENTS, END OF PERIOD	772.0	515.0
Supplemental disclosure of cash flow information:
Cash paid for income taxes	1.0	0.7
Cash paid for interest expense	$ 18.8	$ 18.8