Investments (Tables)

12 Months Ended

Dec. 31, 2017

Investments, Debt and Equity Securities [Abstract]

Amortized Cost, Gross Unrealized Gains And Losses, Fair Value And OTTI

The following tables show the cost or amortized cost, gross unrealized gains and losses, fair value and other-than-temporary impairment ("OTTI") included within accumulated other comprehensive income of the Company's fixed maturity and equity securities as of the dates indicated:

	December 31, 2017
	Cost or Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value		OTTI in  AOCI  (1)
Fixed maturity securities:
U.S. government and government   agencies and authorities	$	180.6	$	3.2	$	(1.2	)	$	182.6	$	—
States, municipalities and political   subdivisions	302.3		24.0		(0.1		)	326.2		—
Foreign governments	524.8		72.3		(0.3		)	596.8
Asset-backed	188.4		1.9		(0.1		)	190.2		1.0
Commercial mortgage-backed	38.6		0.2		(0.7		)	38.1		—
Residential mortgage-backed	1,084.2		32.5		(7.3		)	1,109.4		9.2
U.S. corporate	4,774.2		602.1		(5.0		)	5,371.3		17.4
Foreign corporate	1,663.4		188.6		(4.0		)	1,848.0		—
Total fixed maturity securities	$	8,756.5	$	924.8	$	(18.7	)	$	9,662.6	$	27.6
Equity securities:
Common stocks	$	9.3	$	8.4	$	—		$	17.7	$	—
Non-redeemable preferred stocks	307.0		43.8		(0.5		)	350.3		—
Total equity securities	$	316.3	$	52.2	$	(0.5	)	$	368.0	$	—

	December 31, 2016
	Cost or Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value		OTTI in AOCI (1)
Fixed maturity securities:
U.S. government and government   agencies and authorities	$	172.8	$	3.4	$	(1.3	)	$	174.9	$	—
States, municipalities and political   subdivisions	446.9		29.6		(0.4		)	476.1		—
Foreign governments	508.9		60.5		(0.9		)	568.5		—
Asset-backed	2.6		1.2		(0.1		)	3.7		1.1
Commercial mortgage-backed	39.3		0.1		(1.0		)	38.4		—
Residential mortgage-backed	1,071.2		38.1		(8.0		)	1,101.3		12.8
U.S. corporate	5,022.7		454.1		(15.6		)	5,461.2		15.6
Foreign corporate	1,606.4		147.2		(5.6		)	1,748.0		2.2
Total fixed maturity securities	$	8,870.8	$	734.2	$	(32.9	)	$	9,572.1	$	31.7
Equity securities:
Common stocks	$	11.9	$	8.9	$	—		$	20.8	$	—
Non-redeemable preferred stocks	369.9		31.8		(1.1		)	400.6		—
Total equity securities	$	381.8	$	40.7	$	(1.1	)	$	421.4	$	—

(1) Represents the amount of OTTI recognized in AOCI. Amount includes unrealized gains and losses on impaired securities relating to changes in the value of such securities subsequent to the impairment measurement date.

Amortized Cost And Fair Value Of Fixed Maturity Securities By Contractual Maturity

The cost or amortized cost and fair value of fixed maturity securities as of December 31, 2017 by contractual maturity are shown below. Actual maturities may differ from contractual maturities because issuers of the securities may have the right to call or prepay obligations with or without call or prepayment penalties. 

	Cost or Amortized Cost		Fair Value
Due in one year or less	$	210.3	$	213.1
Due after one year through five years	1,714.2		1,758.6
Due after five years through ten years	1,749.0		1,825.3
Due after ten years	3,771.8		4,527.9
Total	7,445.3		8,324.9
Asset-backed	188.4		190.2
Commercial mortgage-backed	38.6		38.1
Residential mortgage-backed	1,084.2		1,109.4
Total	$	8,756.5	$	9,662.6

The cost or amortized cost and fair value of available-for-sale fixed maturity securities in an unrealized loss position as of December 31, 2017, by contractual maturity, is shown below:

	Cost or Amortized Cost		Fair Value
Due in one year or less	$	22.2	$	22.1
Due after one year through five years	504.0		500.2
Due after five years through ten years	412.6		407.6
Due after ten years	125.4		123.7
Total	1,064.2		1,053.6
Asset-backed	27.7		27.6
Commercial mortgage-backed	13.1		12.4
Residential mortgage-backed	387.5		380.2
Total	$	1,492.5	$	1,473.8

Categories Of Net Investment Income

Major categories of net investment income were as follows:

	Years Ended December 31,
	2017			2016			2015
Fixed maturity securities	$	411.8		$	419.3		$	486.2
Equity securities	22.8			25.2			29.9
Commercial mortgage loans on real estate	31.5			41.7			72.7
Short-term investments	7.2			5.5			2.0
Other investments	25.2			24.2			40.3
Cash and cash equivalents	15.8			17.5			18.4
Revenues from consolidated investment entities (1)	9.8			—			—
Total investment income	524.1			533.4			649.5
Investment expenses	(21.9		)	(17.7		)	(23.3		)
Expenses from consolidated investment entities (1)	(8.4		)	—			—
Net investment income	$	493.8		$	515.7		$	626.2

(1) The net of revenues and expenses from consolidated investment entities of $1.4 million for 2017 includes $0.6 million and $0.5 million of interest income from the Company's direct investment in two CLOs and the real estate fund, respectively, and $0.3 million related to investment management fees. Refer to Note 6, VIE, for further detail.

Proceeds From Sales Of Available-For-Sale Securities And The Gross Realized Gains And Gross Realized Losses

The following table summarizes the proceeds from sales of available-for-sale securities and the gross realized gains and gross realized losses that have been recognized in the statement of operations as a result of those sales:

	For the Years Ended December 31,
	2017		2016		2015
Proceeds from sales	$	3,018.2	$	4,610.7	$	2,568.2
Gross realized gains (1)	43.5		209.5		65.1
Gross realized losses (2)	12.2		65.2		31.7

(1) The year ended December 31, 2016 gross realized gains includes $150.7 million related to the sale of Assurant Employee Benefits as described in Note 4, Dispositions and Exit Activities.

(2)

The year ended December 31, 2016 gross realized losses includes $16.4 million related to the sale of Assurant Employee Benefits as described in Note 4, Dispositions and Exit Activities.

Net Realized Gains (Losses), Including Other-Than-Temporary Impairments

The following table sets forth the net realized gains (losses), including OTTI, recognized in the statement of operations:

	Years Ended December 31,
	2017			2016			2015
Net realized gains (losses) related to sales and other:
Fixed maturity securities	$	22.0		$	128.9		$	13.3
Equity securities	7.7			17.3			19.0
Commercial mortgage loans on real estate	1.3			21.8			0.8
Other investments	1.0			1.1			3.7
Consolidated investment entities (1)	(1.0		)	—			—
Total net realized gains related to sales and other (2)	31.0			169.1			36.8
Net realized losses related to other-than-temporary impairments:
Fixed maturity securities	(0.4		)	(0.7		)	(5.0		)
Other investments	(0.5		)	(6.2		)	—
Total net realized losses related to other-than-temporary impairments	(0.9		)	(6.9		)	(5.0		)
Total net realized gains	$	30.1		$	162.2		$	31.8

(1) Consists of the net realized gains (losses) from the change in fair value of the Company's direct investment in two CLOs. Refer to Note 6, VIE, for further detail.

(2)

The year ended December 31, 2016 net gains includes $146.7 million related to the sale of Assurant Employee Benefits as described in Note 4.

Credit Loss Impairments Recognized

The following table sets forth the amount of credit loss impairments recognized within the results of operations on fixed maturity securities held by the Company as of the dates indicated, for which a portion of the OTTI loss was recognized in AOCI, and the corresponding changes in such amounts:

	Years Ended December 31,
	2017			2016			2015
Balance, beginning of year	$	24.9		$	32.4		$	35.4
Additions for credit loss impairments recognized in the current period   on securities previously impaired	—			0.5			—
Additions for credit loss impairments recognized in the current period   on securities not previously impaired	—			—			2.6
Reductions for increases in cash flows expected to be collected that are   recognized over the remaining life of the security	(2.4		)	(3.6		)	(2.4		)
Reductions for credit loss impairments previously recognized on   securities which matured, paid down, prepaid or were sold during the   period	(4.4		)	(4.4		)	(3.2		)
Balance, end of year	$	18.1		$	24.9		$	32.4

Duration Of Gross Unrealized Losses On Fixed Maturity Securities And Equity Securities

The investment category and duration of the Company’s gross unrealized losses on fixed maturity securities and equity securities as of December 31, 2017 and 2016 were as follows:

	December 31, 2017
	Less than 12 months					12 Months or More					Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
Fixed maturity securities:
U.S. government and government   agencies and authorities	$	104.2	$	(0.7	)	$	43.3	$	(0.5	)	$	147.5	$	(1.2	)
States, municipalities and political   subdivisions	—		—			2.4		(0.1		)	2.4		(0.1		)
Foreign governments	24.4		(0.2		)	0.8		(0.1		)	25.2		(0.3		)
Asset-backed	27.6		(0.1		)	—		—			27.6		(0.1		)
Commercial mortgage-backed	—		—			12.4		(0.7		)	12.4		(0.7		)
Residential mortgage-backed	217.3		(2.4		)	162.9		(4.9		)	380.2		(7.3		)
U.S. corporate	562.8		(4.5		)	30.0		(0.5		)	592.8		(5.0		)
Foreign corporate	266.7		(3.5		)	19.0		(0.5		)	285.7		(4.0		)
Total fixed maturity securities	$	1,203.0	$	(11.4	)	$	270.8	$	(7.3	)	$	1,473.8	$	(18.7	)
Equity securities:
Non-redeemable preferred stocks	$	13.8	$	(0.2	)	$	8.7	$	(0.3	)	$	22.5	$	(0.5	)

	December 31, 2016
	Less than 12 months					12 Months or More					Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
Fixed maturity securities:
U.S. government and government   agencies and authorities	$	91.0	$	(1.3	)	$	—	$	—		$	91.0	$	(1.3	)
States, municipalities and political   subdivisions	16.9		(0.4		)	—		—			16.9		(0.4		)
Foreign governments	98.8		(0.9		)	—		—			98.8		(0.9		)
Asset-backed	—		—			1.0		(0.1		)	1.0		(0.1		)
Commercial mortgage-backed	33.2		(1.0		)	—		—			33.2		(1.0		)
Residential mortgage-backed	347.5		(7.9		)	2.2		(0.1		)	349.7		(8.0		)
U.S. corporate	940.4		(13.1		)	34.1		(2.5		)	974.5		(15.6		)
Foreign corporate	227.3		(4.6		)	7.6		(1.0		)	234.9		(5.6		)
Total fixed maturity securities	$	1,755.1	$	(29.2	)	$	44.9	$	(3.7	)	$	1,800.0	$	(32.9	)
Equity securities:
Non-redeemable preferred stocks	$	64.4	$	(1.0	)	$	1.9	$	(0.1	)	$	66.3	$	(1.1	)

Credit Quality Indicators For Commercial Mortgage Loans

The following summarizes the Company's loan-to-value and average debt-service coverage ratios as of the dates indicated:

	December 31, 2017
Loan-to-Value	Carrying Value			% of Gross Mortgage Loans		Debt-Service Coverage Ratio
70% and less	$	671.2		100.0	%	2.05
Less valuation allowance	(1.0		)
Net commercial mortgage loans	$	670.2

	December 31, 2016
Loan-to-Value	Carrying Value			% of Gross Mortgage Loans		Debt-Service Coverage Ratio
70% and less	$	595.5		95.1	%	1.92
71 – 80%	9.9			1.6	%	1.15
81 – 95%	16.1			2.5	%	1.27
Greater than 95%	4.8			0.8	%	3.86
Gross commercial mortgage loans	626.3			100.0	%	1.91
Less valuation allowance	(2.3		)
Net commercial mortgage loans	$	624.0