Basis of Presentation and Accounting Policies (Details) - USD ($) $ in Millions		1 Months Ended	3 Months Ended		4 Months Ended	5 Months Ended	9 Months Ended
	Jan. 01, 2018	Jun. 30, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	May 31, 2018	Sep. 30, 2018	Sep. 30, 2017	Jun. 01, 2018	Dec. 31, 2017	Jun. 30, 2017	Dec. 31, 2016
Sale of HHI		On May 31, 2018 the Company's indirect parent, Hartford Holding, Inc. ("HHI") completed the sale of the Company's parent to a group of investors led by Cornell Capital LLC, Atlas Merchant Capital LLC, TRB Advisors LP, Global Atlantic Financial Group ("Global Atlantic"), Pine Brook and J. Safra Group. Although Talcott Resolution Life Insurance Company is no longer affiliated with The Hartford Financial Services Group, Inc. ("The Hartford") or any of its subsidiaries, The Hartford retained a 9.7 percent ownership interest in HHLP. On June 1, 2018, TL executed reinsurance agreements to reinsure certain fixed immediate and deferred annuity contracts, variable payout separate account annuity contracts, standard mortality structured settlements, and period certain structured settlement annuity contracts to Commonwealth Annuity and Life Insurance Company ("Commonwealth"), a subsidiary of Global Atlantic which is a member of the acquiring investment group. TL reinsured an 85% quota share, except 75% for standard mortality structured settlements, in exchange for a $357 ceding commission that was fixed based on reinsuring approximately $9.3 billion of reserves as of December 31, 2016, plus annuitizations through closing and annuitizations from market value adjusted annuities post-close. The reinsurance agreement was executed after the Talcott Acquisition Date and as such, the accounting for the agreement was recorded after the TL balance sheet was adjusted to fair value in purchase and pushdown accounting. A deferred gain of approximately $1 billion was recorded in Other liabilities on the Condensed Consolidated Balance Sheet related to this reinsurance agreement and will be amortized over the life of the underlying policies reinsured.
Tax Cuts and Jobs Act of 2017, Reclassification from AOCI to Retained Earnings							$ 193
Equity securities, available-for-sale, at fair value (cost: December 31, 2017 Predecessor Company - $140)			$ 0		$ 0		0			$ 154
Investments and Cash									$ 27,038
Present Value of Future Insurance Profits, Net			818	$ 0	818	$ 0	818	$ 0	805	0		$ 0
Deferred Income Tax Assets, Net			1,013		1,013		1,013		998	556
Intangible Assets, Net (Excluding Goodwill)			53		53		53		55	0
Reinsurance Recoverables, Including Reinsurance Premium Paid			29,819		29,819		29,819		22,615	20,785
Separate Account Assets			106,829		106,829		106,829		110,773	115,834
Assets			159,103		159,103		159,103		162,284	168,732
Liability for Future Policy Benefits			18,292		18,292		18,292		18,057	14,482
Policyholder Funds			28,963		28,963		28,963		29,560	29,228
Other Liabilities			3,250		3,250		3,250		2,127	2,508
Separate Accounts, Liability			106,829		106,829		106,829		110,773	115,834
Liabilities			157,334		157,334		157,334		160,517	162,052
Stockholders' Equity Attributable to Parent			1,769	7,715	1,769	5,810	1,769	7,715	1,767	6,680
Liabilities and Equity			159,103		159,103		159,103		162,284	168,732
Fee Income [Member] | Other fee revenues [Member]
Fee income and other			24	14	32	40		43
Equity Securities [Member]
Equity securities, available-for-sale, at fair value (cost: December 31, 2017 Predecessor Company - $140)			154		154		154			154
Accumulated Net Unrealized Investment Gain (Loss)
OCI, before Reclassifications	$ 11		(50)	45	(125)
Stockholders' Equity Attributable to Parent		$ (75)	$ (124)	$ 931	$ (124)	$ 774	$ (124)	$ 931	$ 0	$ 1,022	$ 899	$ 693