Basis of Presentation and Significant Accounting Policies (Details) - USD ($) $ in Millions			3 Months Ended			6 Months Ended
	Jan. 01, 2018	Dec. 03, 2017	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
TaxCutsAndJobsActOf2017ReclassificationFromAociToRetainedEarningsTaxEffect	$ (88)
Equity securities, AFS			$ 0			$ 0		$ 1,012
Fee income			327		$ 286	650	$ 564
Other revenues			24		23	44	42
Total revenues subject to updated guidance			352		309	694	606
Operating Expense [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Distribution Costs					46		92
Net Unrealized Gain on Securities
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of accounting change net of income taxes								273
Net Unrealized Gain on Securities | Equity Securities [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Equity securities, AFS	1,000
Discontinued Operations, Held-for-sale [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
TaxCutsAndJobsActOf2017ReclassificationFromAociToRetainedEarningsTaxEffect				$ (193)
Cumulative effect of accounting change net of income taxes	10
Corporate
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Fee income			4		0	6	1
Other revenues			2		0	2	0
Continuing Operations [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
TaxCutsAndJobsActOf2017ReclassificationFromAociToRetainedEarningsTaxEffect	(105)
Installment billing fees | Operating Segments | Commercial Lines
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Fee income			8		9	17	19
Installment billing fees | Operating Segments | Personal Lines
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Fee income			10		11	20	22
Insurance servicing revenues | Operating Segments | Personal Lines
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other revenues			23		23	42	42
Administrative services | Operating Segments | Group Benefits
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Fee income			44		19	88	38
Advisor, distribution and other management fees | Operating Segments | Mutual Funds
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Fee income			239		220	477	431
Other fees | Operating Segments | Mutual Funds
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Fee income			22		$ 27	42	$ 53
Maximum [Member] | Discontinued Operations, Held-for-sale [Member] | Other Income [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Discontinued Operation, Period of Continuing Involvement after Disposal		24 months
Equity Securities [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of accounting change net of income taxes	83
Equity securities, AFS								$ 1,012
Shadow DAC [Member] | Discontinued Operations, Held-for-sale [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of accounting change net of income taxes	$ 10