Basis of Presentation and Accounting Policies Level 4 (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncements and Changes in Accounting Principles [Text Block]	On January 1, 2016 the Company adopted new consolidation guidance issued by the Financial Accounting Standards Board ("FASB"). The updates revise when to consolidate variable interest entities ("VIEs") and general partners’ investments in limited partnerships, end the deferral granted for applying the VIE guidance to certain investment companies, and reduce the number of circumstances where a decision maker’s or service provider’s fee arrangement is deemed to be a variable interest in an entity. The updates also modify guidance for determining whether limited partnerships are VIEs or voting interest entities. The new guidance did not have a material effect on the Company’s Consolidated Financial Statements.
Available-for-sale Securities, Equity Securities	$ 152	$ 459
Liabilities	162,525	167,188
Stockholders' Equity Attributable to Parent	7,821	8,162
Maximum uncollateralized threshold for derivative counter party, single level entity	$ 10
Gross profit estimates term	20 years
Statutory Accounting Practices, Dividends Paid with Approval of Regulatory Agency	$ 750	0	$ 800
Reinsurance Recoverables	20,725	20,499
Other Comprehensive Income (Loss), Net of Tax	129	(628)	$ 647
Fair Value, Inputs, Level 2 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Available-for-sale Securities, Equity Securities	$ 88	$ 25
HIG_Accounting Standards Update 2020 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncements and Changes in Accounting Principles [Text Block]	The FASB issued updated guidance for recognition and measurement of credit losses on financial instruments. The new guidance will replace the “incurred loss” approach with an “expected loss” model for recognizing credit losses for instruments carried at other than fair value, which will initially result in the recognition of greater allowances for losses. The allowance will be an estimate of credit losses expected over the life of debt instruments, such as mortgage loans, reinsurance recoverables and receivables. Credit losses on available-for-sale (“AFS”) debt securities carried at fair value will continue to be measured as other-than-temporary impairments (“OTTI”) when incurred; however, the losses will be recognized through an allowance and no longer as an adjustment to the cost basis. Recoveries of OTTI will be recognized as reversals of valuation allowances and no longer accreted as investment income through an adjustment to the investment yield. The allowance on AFS securities cannot cause the net carrying value to be below fair value and, therefore, it is possible that increases in fair value due to decreases in market interest rates could cause the reversal of a valuation allowance and increase net income. The new guidance will also require purchased financial assets with a more-than-insignificant amount of credit deterioration since original issuance to be recorded based on contractual amounts due and an initial allowance recorded at the date of purchase. The guidance is effective January 1, 2020 through a cumulative-effect adjustment to retained earnings for the change in the allowance for credit losses for debt instruments carried at other than fair value. No allowance will be recognized at adoption for AFS debt securities; rather, their cost basis will be evaluated for an allowance for OTTI prospectively. Early adoption is permitted as of January 1, 2019. The Company has not yet determined the timing for adoption or estimated the effect on the Company’s consolidated financial statements. Significant implementation matters yet to be addressed include estimating lifetime expected losses on debt instruments carried at other than fair value, determining the impact of valuation allowances on the effective interest method for recognizing interest income from AFS securities, updating our investment accounting system functionality to adjust valuation allowances based on changes in fair value and developing an implementation plan.
HIG_Accounting Standards Update 2014_09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Description	The FASB issued updated guidance for recognizing revenue. The guidance excludes insurance contracts and financial instruments. Revenue is to be recognized when, or as, goods or services are transferred to customers in an amount that reflects the consideration that an entity is expected to be entitled in exchange for those goods or services, and this accounting guidance is similar to current accounting for many transactions. This guidance is effective retrospectively on January 1, 2018, with a choice of restating prior periods or recognizing a cumulative effect for contracts in place as of the adoption. Early adoption is permitted as of January 1, 2017. The Company will adopt on January 1, 2018 and has not determined its method for adoption. The adoption is not expected to have a material effect on the Company’s Consolidated Financial Statements.
HIG_Accounting Standards Update 2016-01 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Description	The FASB issued updated guidance for the recognition and measurement of financial instruments. The new guidance will require investments in equity securities to be measured at fair value with any changes in valuation reported in net income except for those equity securities that result in consolidation or are accounted for under the equity method of accounting. The new guidance will also require a deferred tax asset resulting from net unrealized losses on available-for-sale fixed maturities that are recognized in accumulated other comprehensive income (loss) ("AOCI") to be evaluated for recoverability in combination with the Company’s other deferred tax assets. Under existing guidance, the Company measures investments in equity securities, available-for-sale, at fair value with changes in fair value reported in other comprehensive income. As required, the Company will adopt the guidance effective January 1, 2018 through a cumulative effect adjustment to retained earnings. Early adoption is not allowed. The impact to the Company will be increased volatility in net income beginning in 2018. Any difference in the evaluation of deferred tax assets may also affect stockholder's equity. Cash flows will not be affected. The impact will depend on the composition of the Company’s investment portfolio in the future and changes in fair value of the Company’s investments.
Net Income Impact [Member] | HIG_Accounting Standards Update 2016-01 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Unrealized Loss on Securities	$ 7
Available-for-sale Securities [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Available-for-sale Securities, Equity Securities	152
Available-for-sale Securities [Member] | Accumulated Other-than-Temporary Impairment Attributable to Parent [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other Comprehensive Income (Loss), Net of Tax	$ 7