Investments (Net Realized Gains (Losses), Including Other-Than-Temporary Impairments) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	[1]	Mar. 31, 2015
Gain (Loss) on Investments [Line Items]
Net realized gains related to sales and other	$ 162,366		$ 6,525
Net realized losses related to other-than- temporary impairments	(648)		(2,570)
Total net realized gains	161,718		3,955
Fixed maturity securities
Gain (Loss) on Investments [Line Items]
Net realized gains related to sales and other	139,149		5,513
Net realized losses related to other-than- temporary impairments	(648)		(2,570)
Equity securities
Gain (Loss) on Investments [Line Items]
Net realized gains related to sales and other	9,806		874
Commercial Mortgage Loans On Real Estate
Gain (Loss) on Investments [Line Items]
Net realized gains related to sales and other	12,453		0
Other investments
Gain (Loss) on Investments [Line Items]
Net realized gains related to sales and other	$ 958		$ 138

[1] (a)2016 includes $146,727 related to the sale of Assurant Employee Benefits mainly through reinsurance transactions.