Fair Value Disclosures (Narrative) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Dec. 31, 2010	Dec. 31, 2011	Dec. 31, 2010		Dec. 31, 2009		Dec. 31, 2008
Fair Value Disclosures [Abstract]
Loan valuation allowance on individually impaired commercial mortgage loan			$ 22,092
Principal balance of individually impaired commercial mortgage loan	22,092	15,760	22,092
Goodwill, carrying amount	619,779	639,097	619,779		926,398		1,001,899
Implied fair value of goodwill		0	306,381	[1]	83,000	[2]
Goodwill, impairment charges	1,650,320	1,650,320	1,650,320		1,343,939		1,260,939
Impairment charges	$ 47,612	$ 0	$ 47,612		$ 0

[1] Represents impairment of Assurant Employee Benefits and Assurant Health reporting units. See Notes 2 and 5 for further information.

[2] Represents impairment of Assurant Employee Benefits reporting unit. See Notes 2 and 5 for further information.