Segment Information (Financial Information by Segment) (Details) $ in Thousands		3 Months Ended
	Mar. 01, 2016 USD ($)	Mar. 31, 2016 USD ($) segment		Mar. 31, 2015 USD ($)	Dec. 31, 2015 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment		5
Revenues
Net earned premiums		$ 1,415,238		$ 2,159,562
Net investment income		135,707		152,273
Net realized gains on investments		161,718	[1]	3,955
Amortization of deferred gain on disposal of businesses		47,596	[2]	3,258
Gain on pension plan curtailment		29,578		0
Fees and other income		357,690		279,562
Total revenues		2,147,527		2,598,610
Benefits, losses and expenses
Policyholder benefits		543,816		1,210,727
Amortization of deferred acquisition costs and value of business acquired		334,342		369,003
Underwriting, general and administrative expenses		917,359		921,909
Interest expense		14,503		13,778
Total benefits, losses and expenses		1,810,020		2,515,417
Segment income (loss) before provision (benefit) for income tax		337,507		83,193
Provision (benefit) for income taxes		117,189		33,149
Net income		220,318		50,044
Total assets		30,287,195			$ 30,036,402
Operating Segments | Solutions
Revenues
Net earned premiums		738,924		754,477
Net investment income		88,923		92,191
Net realized gains on investments		0	[1]	0
Amortization of deferred gain on disposal of businesses		0	[2]	0
Gain on pension plan curtailment		0
Fees and other income		238,109		173,068
Total revenues		1,065,956		1,019,736
Benefits, losses and expenses
Policyholder benefits		226,751		215,548
Amortization of deferred acquisition costs and value of business acquired		269,010		265,032
Underwriting, general and administrative expenses		501,210		459,284
Interest expense		0		0
Total benefits, losses and expenses		996,971		939,864
Segment income (loss) before provision (benefit) for income tax		68,985		79,872
Provision (benefit) for income taxes		21,851		25,513
Net income		47,134		54,359
Total assets		14,778,747			14,356,484
Operating Segments | Specialty Property
Revenues
Net earned premiums		469,609		528,446
Net investment income		18,344		20,515
Net realized gains on investments		0	[1]	0
Amortization of deferred gain on disposal of businesses		0	[2]	0
Gain on pension plan curtailment		0
Fees and other income		107,762		84,236
Total revenues		595,715		633,197
Benefits, losses and expenses
Policyholder benefits		179,472		204,603
Amortization of deferred acquisition costs and value of business acquired		59,474		92,069
Underwriting, general and administrative expenses		241,434		223,612
Interest expense		0		0
Total benefits, losses and expenses		480,380		520,284
Segment income (loss) before provision (benefit) for income tax		115,335		112,913
Provision (benefit) for income taxes		38,984		37,826
Net income		76,351		75,087
Total assets		3,628,056			3,648,738
Operating Segments | Health
Revenues
Net earned premiums		28,734		609,742
Net investment income		3,938		7,007
Net realized gains on investments		0	[1]	0
Amortization of deferred gain on disposal of businesses		0	[2]	0
Gain on pension plan curtailment		0
Fees and other income		5,118		15,976
Total revenues		37,790		632,725
Benefits, losses and expenses
Policyholder benefits		19,112		604,763
Amortization of deferred acquisition costs and value of business acquired		0		4,273
Underwriting, general and administrative expenses		52,955		129,178
Interest expense		0		0
Total benefits, losses and expenses		72,067		738,214
Segment income (loss) before provision (benefit) for income tax		(34,277)		(105,489)
Provision (benefit) for income taxes		(7,104)		(21,520)
Net income		(27,173)		(83,969)
Total assets		960,965			1,437,032
Operating Segments | Employee Benefits
Revenues
Net earned premiums		177,971	[3]	266,897
Net investment income		17,340	[3]	27,821
Net realized gains on investments		0	[1],[3]	0
Amortization of deferred gain on disposal of businesses		0	[2],[3]	0
Gain on pension plan curtailment		0
Fees and other income		4,244	[3]	6,274
Total revenues		199,555	[3]	300,992
Benefits, losses and expenses
Policyholder benefits		118,481	[3]	185,813
Amortization of deferred acquisition costs and value of business acquired		5,858	[3]	7,629
Underwriting, general and administrative expenses		58,469	[3]	91,339
Interest expense		0	[3]	0
Total benefits, losses and expenses		182,808	[3]	284,781
Segment income (loss) before provision (benefit) for income tax		16,747	[3]	16,211
Provision (benefit) for income taxes		6,277	[3]	6,063
Net income		10,470	[3]	10,148
Total assets		0			2,190,808
Operating Segments | Corporate & Other
Revenues
Net earned premiums		0		0
Net investment income		7,162		4,739
Net realized gains on investments		161,718	[1]	3,955
Amortization of deferred gain on disposal of businesses		47,596	[2]	3,258
Gain on pension plan curtailment		29,578
Fees and other income		2,457		8
Total revenues		248,511		11,960
Benefits, losses and expenses
Policyholder benefits		0		0
Amortization of deferred acquisition costs and value of business acquired		0		0
Underwriting, general and administrative expenses		63,291		18,496
Interest expense		14,503		13,778
Total benefits, losses and expenses		77,794		32,274
Segment income (loss) before provision (benefit) for income tax		170,717		(20,314)
Provision (benefit) for income taxes		57,181		(14,733)
Net income		113,536		$ (5,581)
Total assets		$ 10,919,427			$ 8,403,340
Employee Benefits | Disposal Group, Not Discontinued Operations
Revenues
Amortization of deferred gain on disposal of businesses	$ 44,593
Benefits, losses and expenses
Assets sold	$ 146,727

[1] Includes $146,727 related to assets transferred to Sun Life as part of the Assurant Employee Benefits sale on March 1, 2016.

[2] Includes $44,593 related to the additional deferred gain related to the Assurant Employee Benefits sale on March 1, 2016.

[3] Assurant Employee Benefits amounts represent January and February results of operations prior to the sale on March 1, 2016.