Derivatives (Narrative) (Details) - USD ($)		3 Months Ended		9 Months Ended		12 Months Ended
	Aug. 04, 2017	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Maximum Amount of Future Payments under Credit Default Swaps		$ 11,507,000,000		$ 11,507,000,000		$ 11,375,000,000
Estimated Fair Value of Credit Default Swaps		221,000,000		221,000,000		271,000,000
Estimated Fair Value Assets		7,288,000,000		7,288,000,000		8,551,000,000
Estimated Fair Value Liabilities		4,517,000,000		4,517,000,000		4,339,000,000
Excess securities collateral received on derivatives		165,000,000		165,000,000		$ 253,000,000
Derivative Instruments, Gain (Loss) [Line Items]
Net derivatives gains (losses)		167,000,000	$ 301,000,000	355,000,000	$ 549,000,000
Derivative Instrument Detail [Abstract]
Change in fair value of derivatives excluded from the assessment of hedge effectiveness		(7,000,000)	(6,000,000)	(27,000,000)	(30,000,000)
Net amounts reclassified into net derivatives gains (losses) on discontinued cash flow hedges		1,000,000	$ (4,000,000)	$ 6,000,000	$ 16,000,000
Hedging exposure to variability in future cash flows for specific length of time				4 years		5 years
Accumulated Other Comprehensive Income Loss		$ 1,300,000,000		$ 1,300,000,000		$ 1,500,000,000
Deferred net gains (losses) expected to be reclassified to earnings				$ 0
Immateriality of cash flow effectiveness		0	0	0	0
Cumulative foreign currency translation gain (loss) recorded in accumulated other comprehensive income (loss) for net investment in foreign operations hedges		$ 236,000,000		$ 236,000,000		309,000,000
Potential future recoveries available to offset maximum amount of future payments under credit default swaps		16,000,000		16,000,000		27,000,000
Excess securities collateral provided on derivatives		252,000,000		252,000,000		272,000,000
Securities collateral received which the company is permitted to sell or repledge, amount that has been sold or repledged		0		0
Nonperformance Risk [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net derivatives gains (losses)		(20,000,000)	$ (21,000,000)	(25,000,000)	$ (162,000,000)
Over the Counter [Member]
Derivatives, Fair Value [Line Items]
Excess securities collateral received on derivatives		(154,000,000)		(154,000,000)		(108,000,000)
Excess securities collateral provided on derivatives		(254,000,000)		(254,000,000)		(305,000,000)
Cash collateral on derivative assets		(3,189,000,000)		(3,189,000,000)		(4,169,000,000)
Exchange-traded
Derivatives, Fair Value [Line Items]
Excess securities collateral received on derivatives		(524,000,000)		(524,000,000)		(522,000,000)
Excess securities collateral provided on derivatives		(84,000,000)		(84,000,000)		(89,000,000)
Cash collateral on derivative assets		0		0		0
Cash Flow Hedging [Member] | Discontinued Operations | Brighthouse Financial, Inc
Derivative Instrument Detail [Abstract]
Reduction of Deferred Gains within AOCI	$ 414,000,000		(40,000,000)		(92,000,000)
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net			$ 1,000,000		$ 16,000,000
Accrued Liabilities [Member]
Derivatives, Fair Value [Line Items]
Estimated Fair Value Assets		86,000,000		86,000,000		75,000,000
Estimated Fair Value Liabilities		$ (38,000,000)		$ (38,000,000)		$ (49,000,000)