Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018		Jun. 30, 2017
Cash flows from operating activities:
Net income	$ 66.6		$ 82.7
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Amortization and depreciation	13.8		15.9
Share-based payments expense	11.0		7.6
Deferred income tax benefit, net	(6.9)		(4.7)
Net realized investment losses (gains)	5.2		(19.1)
Undistributed earnings from alternative investment portfolio	(13.9)		(32.9)
Loss on disposals of fixed assets, net	0.0		1.7
Change in:
Accrued investment income	(1.2)		(2.1)
Receivables	(53.3)		(103.9)
Deferred acquisition costs	(1.5)		(13.8)
Ceded unearned premiums	(87.4)		(41.0)
Reserves for losses and loss adjustment expenses	(71.1)		85.4
Unearned premiums	67.0		53.3
Ceded reinsurance payable and funds held	80.2		57.0
Income taxes	14.9		5.9
Accrued underwriting expenses	(29.4)		(21.7)
Other, net	131.9		(33.0)
Cash provided by (used in) operating activities	125.9		37.3
Cash flows from investing activities:
Sales of fixed maturity investments	882.0		785.8
Maturities and mandatory calls of fixed maturity investments	288.7		335.1
Sales of equity securities	104.9		107.5
Sales of other investments	38.1		65.1
Purchases of fixed maturity investments	(1,237.5)		(1,381.7)
Purchases of equity securities	(113.3)		(67.5)
Purchases of other investments	(23.3)		(16.8)
Change in foreign regulatory deposits and voluntary pools	13.1		(9.5)
Change in short-term investments	(80.7)		309.9
Settlements of foreign currency exchange forward contracts	2.3		0.5
Acquisition of Maybrooke, net of cash acquired			(105.2)
Cash acquired with acquisition of Ariscom	15.6
Purchases of fixed assets	(11.0)		(10.0)
Other, net	(16.7)		(27.7)
Cash used in investing activities	(137.8)		(14.5)
Cash flows from financing activities:
Additional long-term borrowings	0.0		125.0
Activity under stock incentive plans	0.2		0.5
Repurchase of Company's common shares	(19.4)		(2.8)
Payment of cash dividends to common shareholders	(18.7)		(16.6)
Cash (used in) provided by financing activities	(37.9)		106.1
Effect of exchange rate changes on cash	(0.1)		(0.4)
Change in cash	(49.9)		128.5
Cash, beginning of year	176.6	[1]	86.0
Cash, end of period	126.7		214.5
Maybrooke [Member]
Cash flows from investing activities:
Acquisition of Maybrooke, net of cash acquired	0.0		(105.2)
Ariscom [Member]
Cash flows from investing activities:
Cash acquired with acquisition of Ariscom	$ 15.6		$ 0.0

[1] Derived from audited consolidated financial statements.