Investments (Net Realized Gains (Losses), Including Other-Than-Temporary Impairments) (Details) - USD ($) $ in Thousands			3 Months Ended		6 Months Ended
		Mar. 01, 2016	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016		Jun. 30, 2015
Gain (Loss) on Investments [Line Items]
Net realized gains related to sales and other			$ 21,679	$ 11,999	$ 184,045	[1]	$ 18,524
Net realized losses related to other-than- temporary impairments			(53)	0	(701)		(2,570)
Total net realized gains			21,626	11,999	183,344		15,954
Fixed maturity securities
Gain (Loss) on Investments [Line Items]
Net realized gains related to sales and other			6,625	6,746	145,774		12,259
Net realized losses related to other-than- temporary impairments			(53)	0	(701)		(2,570)
Equity securities
Gain (Loss) on Investments [Line Items]
Net realized gains related to sales and other			3,337	1,080	13,143		1,954
Commercial Mortgage Loans On Real Estate
Gain (Loss) on Investments [Line Items]
Net realized gains related to sales and other			9,092	0	21,545		0
Other investments
Gain (Loss) on Investments [Line Items]
Net realized gains related to sales and other			$ 2,625	$ 4,173	$ 3,583		$ 4,311
Disposal Group, Not Discontinued Operations | Employee Benefits Segment
Gain (Loss) on Investments [Line Items]
Investments transferred	[2]	$ 146,727

[1] Six months ended June 30, 2016 net gains includes $146,727 related to the sale of Assurant Employee Benefits as described in Note 5.

[2] Reinsurance of existing claims liabilities requires retroactive accounting necessitating losses to be recognized immediately. However, upon transfer of the associated assets supporting the liabilities, the Company recognized realized gains which more than offset the retroactive losses. The Company was required to classify the realized gains as part of net realized gains on investments, within the Consolidated Statements of Operations.