Investments (Proceeds From Sales Of Available-For-Sale Securities And The Gross Realized Gains And Gross Realized Losses) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sales		$ 4,610,681	$ 2,568,166	$ 1,995,368
Gross realized gains	[1]	209,475	65,097	69,184
Gross realized losses	[2]	65,206	$ 31,657	$ 10,681
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Assurant Employee Benefits
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gross realized gains		150,701
Gross realized losses		$ 16,427

[1] Twelve months ended December 31, 2016 gross realized gains includes $150,701 related to the sale of Assurant Employee Benefits as described in Note 5.

[2] Twelve months ended December 31, 2016 gross realized losses includes $16,427 related to the sale of Assurant Employee Benefits as described in Note 5.