Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Millions		6 Months Ended
		Jun. 30, 2019	Jun. 30, 2018
Statement of Cash Flows [Abstract]
Net income attributable to stockholders		$ 309.8	$ 173.0
Noncash revenues, expenses, gains and losses included in income:
Deferred tax expense		53.6	24.7
Amortization of deferred gains on disposal of businesses		(12.5)	(33.5)
Depreciation and amortization		60.1	54.9
Net realized (gains) losses on investments		(46.6)	10.9
Loss on business classified as held for sale		0.0	34.4
Stock based compensation expense		25.7	21.7
Other intangible asset impairment		14.6	0.0
Changes in operating assets and liabilities:
Change in insurance policy reserves and expenses		501.0	(434.0)
Change in premiums and accounts receivable		(99.4)	(39.6)
Change in reinsurance recoverable		85.1	644.8
Change in reinsurance balance payable		(12.7)	(3.4)
Change in funds withheld under reinsurance		34.4	(31.2)
Change in deferred acquisition costs and value of business acquired		(438.6)	(206.1)
Change in accounts payable		194.3	(285.1)
Change in other assets and other liabilities		12.7	103.4
Change in taxes payable		30.1	103.2
Other		14.1	34.2
Net cash provided by operating activities		725.7	172.3
Sales of:
Fixed maturity securities available for sale		1,262.3	1,465.8
Equity securities		52.5	57.2
Other invested assets		22.1	35.6
Maturities, calls, prepayments, and scheduled redemption of:
Fixed maturity securities available for sale		295.9	377.1
Commercial mortgage loans on real estate		32.2	78.3
Purchases of:
Fixed maturity securities available for sale		(1,731.7)	(1,646.8)
Equity securities		(43.8)	(39.4)
Commercial mortgage loans on real estate		(52.3)	(131.6)
Other invested assets		(24.9)	(19.7)
Property and equipment and other		(57.8)	(38.1)
Subsidiaries, net of cash transferred		0.0	(1,213.5)
Consolidated investment entities
Purchases of investments	[1]	(874.0)	(828.3)
Sale of investments	[1]	488.5	294.8
Change in short-term investments		18.9	94.9
Other		2.5	(1.1)
Net cash used in investing activities		(609.6)	(1,514.8)
Financing activities
Issuance of mandatory convertible preferred stock, net of issuance costs	[2]	0.0	276.4
Issuance of debt, net of issuance costs	[3]	0.0	1,286.1
Repayment of debt	[3]	0.0	(350.0)
Issuance of collateralized loan obligation notes	[1]	416.4	404.9
Issuance of debt for consolidated investment entities	[1]	189.1	385.4
Repayment of debt for consolidated investment entities	[1]	(318.1)	(296.3)
Acquisition of common stock		(98.5)	(6.9)
Common stock dividends paid		(75.7)	(60.6)
Preferred stock dividends paid		(9.3)	(4.8)
Withholding on stock based compensation		14.7	6.1
Non-controlling interest		0.0	7.7
Other		0.0	(3.5)
Net cash provided by financing activities		118.6	1,644.5
Effect of exchange rate changes on cash and cash equivalents		1.7	(22.8)
Cash included in business classified as held for sale		0.0	(22.3)
Change in cash and cash equivalents		236.4	256.9
Cash and cash equivalents at beginning of period		1,254.0	996.8
Cash and cash equivalents at end of period		$ 1,490.4	$ 1,253.7

[1] Relates to cash flows from our variable interest entities. Refer to Note 8 for further information.

[2] Refer to Note 14 for additional information.

[3] Refer to Note 11 for additional information.