Consolidated Statements of Cash Flows - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash Flows From Operating Activities
Net income	$ 134.7	$ 168.6
Adjustments to reconcile net income to net cash provided by operating activities:
Net realized investment gains	(21.2)	(5.1)
Net amortization and depreciation	23.0	24.6
Stock-based compensation expense	11.5	8.5
Amortization of defined benefit plan costs	10.5	7.5
Gain on disposal of U.K. motor business		(1.3)
Net loss from repayment of debt		86.1
Deferred income tax expense	(3.1)	10.1
Change in deferred acquisition costs	(45.0)	(27.8)
Change in premiums receivable, net of reinsurance premiums payable	(96.5)	(84.7)
Change in loss, loss adjustment expense and unearned premium reserves	917.5	512.5
Change in reinsurance recoverable	(337.4)	(102.9)
Change in expenses and taxes payable	(53.9)	(29.3)
Other, net	(7.9)	(6.8)
Net cash provided by operating activities	532.2	560.0
Cash Flows From Investing Activities
Proceeds from disposals and maturities of fixed maturities	819.7	1,190.3
Proceeds from disposals of equity securities and other investments	138.2	226.1
Purchase of fixed maturities	(1,296.9)	(1,443.1)
Purchase of equity securities and other investments	(139.8)	(292.2)
Capital expenditures	(10.7)	(12.2)
Other investing activities	(9.7)	12.1
Net cash used in investing activities	(499.2)	(319.0)
Cash Flows From Financing Activities
Proceeds from exercise of employee stock options	19.2	14.8
Proceeds from debt borrowings, net		370.5
Change in cash collateral related to securities lending program	(7.3)	(9.6)
Dividends paid to shareholders	(63.8)	(59.2)
Repayment of debt		(461.3)
Repurchases of common stock	(37.2)	(105.2)
Other financing activities	(3.0)	(11.7)
Net cash used in financing activities	(92.1)	(261.7)
Effect of exchange rate changes on cash	3.7	(2.2)
Net change in cash and cash equivalents	(55.4)	(22.9)
Cash and cash equivalents, beginning of period	282.6	338.8
Cash and cash equivalents, end of period	$ 227.2	$ 315.9