Unaudited Condensed Consolidated Statements Of Cash Flows - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
CASH FLOWS PROVIDED BY OPERATING ACTIVITIES:
Net income	$ 227.5	$ 133.8
Adjustments to reconcile net income to cash provided by operating activities:
Net realized gains on sales of investments	(31.2)	(58.2)
Mark to market adjustments	(89.3)	35.6
Stock compensation expense	8.6	7.9
Undistributed income of equity method investments	15.2	16.0
Changes in:
Reserve for losses and loss expenses, net of reinsurance recoverables	130.2	132.9
Unearned premiums, net of prepaid reinsurance	101.0	160.4
Insurance balances receivable	(216.4)	(162.3)
Reinsurance recoverable on paid losses	22.6	(2.3)
Funds held	361.7	261.5
Reinsurance balances payable	13.3	11.5
Net deferred acquisition costs	(3.7)	(17.6)
Net deferred tax assets	3.2	(2.7)
Accounts payable and accrued liabilities	(47.9)	(54.6)
Other items, net	5.2	(34.5)
Net cash provided by operating activities	500.0	427.4
CASH FLOWS USED IN INVESTING ACTIVITIES:
Purchases of trading securities	(3,257.8)	(2,854.8)
Purchases of other invested assets	(33.2)	(73.1)
Sales of trading securities	2,932.2	2,953.6
Sales of other invested assets	37.3	85.5
Purchases of fixed assets	(1.9)	(18.0)
Change in restricted cash	(17.6)	(26.1)
Net cash paid for acquisitions	(1.2)	(141.5)
Net cash used in investing activities	(342.2)	(74.4)
CASH FLOWS USED IN FINANCING ACTIVITIES:
Dividends paid	(46.2)	(43.2)
Proceeds from the exercise of stock options	3.1	7.4
Share repurchases	(139.5)	(246.4)
Proceeds from other long-term debt	0.0	3.9
Repayment of other long-term debt	(0.2)	0.0
Net cash used in financing activities	(182.8)	(278.3)
Effect of exchange rate changes on foreign currency cash	1.5	(2.2)
NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS	(23.5)	72.5
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	608.0	589.3
CASH AND CASH EQUIVALENTS, END OF PERIOD	584.5	661.8
Supplemental disclosure of cash flow information:
Cash paid for income taxes	1.6	1.9
Cash paid for interest expense	$ 37.9	$ 27.0