VOBA And Other Intangible Assets (Future Amortization Expenses) (Details) - Other Intangible Assets $ in Thousands	12 Months Ended
Dec. 31, 2015 USD ($)
Finite-Lived Intangible Assets [Line Items]
2016	$ 67,079
2017	59,782
2018	47,081
2019	30,837
2020	26,276
Thereafter	46,108
Total	$ 277,163

Expected Amortization Expense of Ending Present Value of Future Insurance Profits, Thereafter

No definition available.

Name:	aiz_ExpectedAmortizationExpenseofEndingPresentValueofFutureInsuranceProfitsThereafter
Namespace Prefix:	aiz_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Expected amortization expense in the fifth year after the balance sheet date of the present value of the future profits of long-duration contracts acquired in a purchase of an insurance enterprise.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 20
-Section S99
-Paragraph 2
-Subparagraph (3)
-URI http://asc.fasb.org/extlink&oid=27015749&loc=d3e569990-122904

+ Details

Name:	us-gaap_ExpectedAmortizationExpenseOfEndingPresentValueOfFutureInsuranceProfitsYearFive
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Expected amortization expense in the fourth year after the balance sheet date of the present value of the future profits of long-duration contracts acquired in a purchase of an insurance enterprise.

+ References

+ Details

Name:	us-gaap_ExpectedAmortizationExpenseOfEndingPresentValueOfFutureInsuranceProfitsYearFour
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Expected amortization expense in the first year after the balance sheet date of the present value of the future profits of long-duration contracts acquired in a purchase of an insurance enterprise.

+ References

+ Details

Name:	us-gaap_ExpectedAmortizationExpenseOfEndingPresentValueOfFutureInsuranceProfitsYearOne
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Expected amortization expense in the third year after the balance sheet date of the present value of the future profits of long-duration contracts acquired in a purchase of an insurance enterprise.

+ References

+ Details

Name:	us-gaap_ExpectedAmortizationExpenseOfEndingPresentValueOfFutureInsuranceProfitsYearThree
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Expected amortization expense in the second year after the balance sheet date of the present value of the future profits of long-duration contracts acquired in a purchase of an insurance enterprise.

+ References

+ Details

Name:	us-gaap_ExpectedAmortizationExpenseOfEndingPresentValueOfFutureInsuranceProfitsYearTwo
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetsNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_OtherIntangibleAssetsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: