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.

No definition available.

+ Details

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

- Definition

The carrying value as of the balance sheet date of the estimated valuation allowance to reduce gross premiums receivable to net realizable value.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(5))
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 13
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919249-210447

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 13
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919249-210447

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953423-111524

Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5074-111524

+ Details

Name:	us-gaap_PremiumsReceivableAllowanceForDoubtfulAccounts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The carrying amount as of the balance sheet date due the entity from (a) agents and insureds, (b) uncollected premiums and (c) others, net of the allowance for doubtful accounts.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.(a),5)
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

+ Details

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

- Definition

Gross amount, as of the balance sheet date, due the entity from (a) agents and insureds, (b) uncollected premiums and (c) others, before deducting the allowance for doubtful accounts.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.5)
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

+ Details

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

- Details

Name:	us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=hig_PremiumsReceivableDueinOneYearorLessExcludingReceivablesforLosswithinaDeductibleandRetrospectivelyRatedPolicyPremiumsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=hig_PremiumsReceivableLossWithinaDeductibleandRetrospectivelyRatedPolicyPremiumsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CreditRatingMoodysAxis=srt_MoodysAaaRatingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CreditRatingMoodysAxis=srt_MoodysAa2RatingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CreditRatingMoodysAxis=srt_MoodysA2RatingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CreditRatingMoodysAxis=srt_MoodysBaa2RatingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CreditRatingMoodysAxis=srt_MoodysBa2RatingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CreditRatingMoodysAxis=hig_MoodysBelowBa2RatingMemberMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Premiums Receivable - Premiums Receivable and Agents' Balances (Details) - USD ($) $ in Millions	Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
Premiums Receivable, Gross	$ 4,624		$ 4,529
ACL	(174)	$ (183)	(145)
Premiums receivable and agents' balances, net of ACL	4,450		4,384
Premiums receivable, excluding receivables for losses within a deductible and retrospectively-rated policy premiums
Financing Receivable, Credit Quality Indicator [Line Items]
Premiums Receivable, Gross	4,027
ACL	(130)	(139)	(85)
Receivables for Loss within a Deductible and Retrospectively-Rated Policy Premiums
Financing Receivable, Credit Quality Indicator [Line Items]
Premiums Receivable, Gross	597
ACL	(44)	$ (44)	$ (60)
Receivables for Loss within a Deductible and Retrospectively-Rated Policy Premiums \| AAA
Financing Receivable, Credit Quality Indicator [Line Items]
Premiums Receivable, Gross	0
Receivables for Loss within a Deductible and Retrospectively-Rated Policy Premiums \| AA
Financing Receivable, Credit Quality Indicator [Line Items]
Premiums Receivable, Gross	139
Receivables for Loss within a Deductible and Retrospectively-Rated Policy Premiums \| A
Financing Receivable, Credit Quality Indicator [Line Items]
Premiums Receivable, Gross	52
Receivables for Loss within a Deductible and Retrospectively-Rated Policy Premiums \| BBB
Financing Receivable, Credit Quality Indicator [Line Items]
Premiums Receivable, Gross	226
Receivables for Loss within a Deductible and Retrospectively-Rated Policy Premiums \| BB
Financing Receivable, Credit Quality Indicator [Line Items]
Premiums Receivable, Gross	103
Receivables for Loss within a Deductible and Retrospectively-Rated Policy Premiums \| Below BB
Financing Receivable, Credit Quality Indicator [Line Items]
Premiums Receivable, Gross	$ 77