Consolidated Statements of Cash Flows - USD ($) $ in Millions		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016
Statement of Cash Flows [Abstract]
Net cash provided by (used in) operating activities		$ 366.4	$ (68.0)
Sales of:
Fixed maturity securities available for sale		2,270.3	1,736.1
Equity securities available for sale		59.1	160.0
Other invested assets		72.6	51.9
Subsidiary, net of cash transferred	[1]	0.0	873.9
Commercial mortgage loans on real estate		0.0	268.8
Maturities, calls, prepayments, and scheduled redemption of:
Fixed maturity securities available for sale		631.5	589.4
Commercial mortgage loans on real estate		102.9	87.0
Purchases of:
Fixed maturity securities available for sale		(2,734.2)	(2,832.4)
Equity securities available for sale		(18.8)	(150.5)
Commercial mortgage loans on real estate		(124.0)	(52.2)
Other invested assets		(71.6)	(79.2)
Property and equipment and other		(43.4)	(66.8)
Subsidiaries, net of cash transferred	[2]	(127.4)	(63.2)
Special Purpose Entities
Purchases of investments	[3]	(265.3)	0.0
Proceeds from sales and redemptions of investments	[3]	36.2	0.0
Change in short-term investments		(31.7)	106.0
Other		1.8	2.5
Net cash (used in) provided by investing activities		(242.0)	631.3
Financing activities
Issuance of debt	[3]	0.0	249.6
Repayment of debt		0.0	(250.0)
Change in tax benefit from share-based payment arrangements		0.0	9.4
Proceeds from Issuance of Secured Debt	[3]	157.7	0.0
Acquisition of common stock		(256.8)	(674.3)
Dividends paid		(88.8)	(95.0)
Withholding on stock based compensation		18.2	25.0
Net cash used in financing activities		(169.7)	(735.3)
Effect of exchange rate changes on cash and cash equivalents		6.1	(5.5)
Adjustments for cash included in business classified as held for sale		0.0	5.9
Change in cash and cash equivalents		(39.2)	(171.6)
Cash and cash equivalents at beginning of period		1,032.0	1,288.3
Cash and cash equivalents at end of period		$ 992.8	$ 1,116.7

[1] Primarily relates to the sale of Assurant's Employee Benefits segment mainly through reinsurance transactions.

[2] 2017 primarily includes the acquisition of Green Tree Insurance Agency, Inc

[3] Refer to Note 7- Investments for additional information regarding 2017 activity.