Dispositions (Narrative) (Details) - USD ($) $ in Thousands			1 Months Ended		3 Months Ended			9 Months Ended	24 Months Ended
		Mar. 01, 2016	Mar. 31, 2016		Mar. 31, 2016		Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net cash consideration from disposal	[1]				$ 914,811		$ 65,002
Disposal Group, Not Discontinued Operations | Employee Benefits Segment
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net cash consideration from disposal		$ 926,174
Consideration from disposal consisting of account renewals		16,000
Estimated gain disposal		638,517
Gain (loss) net of tax		120,077
Gain (loss) on disposal					164,670
Deferred gain on disposal		$ 518,440	$ 473,847	[2]	473,847	[2]
Amortization of deferred gain	[3]		$ 44,593
Pretax income from disposal					$ 16,747		$ 16,211
Scenario, Forecast | Disposal Group, Not Discontinued Operations | Employee Benefits Segment
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Percent of deferred gain to be earned								60.00%	90.00%

[1] Relates to the sale of Assurant's Employee Benefits segment mainly through reinsurance transactions and supplemental and small group self-funded business.

[2] Amount classified as a component of the deferred gain on disposal of businesses within the Consolidated Balance Sheets.

[3] Amount classified as amortization of deferred gain on disposal of businesses within the Consolidated Statements of Operations.