Derivatives (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Derivatives, Fair Value [Line Items]
Estimated Fair Value Assets	$ 15,515		$ 15,515		$ 13,452
Estimated Fair Value Liabilities	7,354		7,354		7,022
Maximum Amount of Future Payments under Credit Default Swaps	10,458		10,458		10,527
Estimated Fair Value of Credit Default Swaps	47		47		175
Excess securities collateral received on derivatives	76		76		$ 87
Derivative Instruments, Gain (Loss) [Line Items]
Net derivatives gains (losses)	(1,833)	$ (65)	$ (1,039)	$ 55
Derivative, Average Remaining Maturity			4 years 2 months		3 years 11 months
Gain (Loss) on Investments	(382)	(109)	$ (535)	427
Derivative Instrument Detail [Abstract]
Net amounts reclassified into net derivatives gains (losses) on discontinued cash flow hedges	(3)	$ (11)	$ 0	$ (15)
Hedging exposure to variability in future cash flows for specific length of time			6 years		6 years
Accumulated Other Comprehensive Income Loss	2,100		$ 2,100		$ 1,800
Deferred net gains (losses) expected to be reclassified to earnings			(106)
Amount and Location of Gains (Losses) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Loss) (Effective Portion)	$ 0		$ 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	$ 1,100		$ 1,100		940
Potential future recoveries available to offset maximum amount of future payments under credit default swaps	345		345		75
Excess securities collateral provided on derivatives	175		175		192
Change in fair value of derivatives excluded from the assessment of hedge effectiveness	(4)	$ (2)	(9)	$ 3
Securities collateral received which the company is permitted to sell or repledge, amount that has been sold or repledged	0		0
Over the Counter [Member]
Derivatives, Fair Value [Line Items]
Cash collateral on derivative assets	(7,151)		(7,151)		(4,153)
Excess securities collateral received on derivatives	(154)		(154)		(395)
Excess securities collateral provided on derivatives	(145)		(145)		(117)
Exchange-traded
Derivatives, Fair Value [Line Items]
Cash collateral on derivative assets	0		0		0
Excess securities collateral received on derivatives	(270)		(270)		(199)
Excess securities collateral provided on derivatives	(161)		(161)		(245)
Hedge Funds [Member]
Derivatives, Fair Value [Line Items]
Maximum Amount of Future Payments under Credit Default Swaps	20		20		15
Estimated Fair Value of Credit Default Swaps	(1)		(1)		1
Ba [Member]
Derivatives, Fair Value [Line Items]
Maximum Amount of Future Payments under Credit Default Swaps	160		160		160
Estimated Fair Value of Credit Default Swaps	0		$ 0		$ (1)
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Average Remaining Maturity			1 year 7 months		2 years 5 months
Nonperformance Risk [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net derivatives gains (losses)	253	5	$ 222	(3)
B
Derivatives, Fair Value [Line Items]
Maximum Amount of Future Payments under Credit Default Swaps	625		625		$ 625
Estimated Fair Value of Credit Default Swaps	0		$ 0		$ 39
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Average Remaining Maturity			5 years 1 month		4 years 11 months
Accrued Liabilities [Member]
Derivatives, Fair Value [Line Items]
Estimated Fair Value Assets	227		$ 227		$ 255
Estimated Fair Value Liabilities	41		41		60
Off-Balance Sheet [Member]
Derivatives, Fair Value [Line Items]
Excess securities collateral received on derivatives	0		0		36
Off-Balance Sheet [Member] | Over the Counter [Member]
Derivatives, Fair Value [Line Items]
Cash collateral on derivative assets	0		0		(263)
MetLife Assurance Limited | Accumulated Other Comprehensive Income (Loss) Foreign Currency Translation Adjustments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Investments		$ 0		$ (77)
Credit Index Product [Member] | Ba [Member]
Derivatives, Fair Value [Line Items]
Maximum Amount of Future Payments under Credit Default Swaps	100		100		100
Estimated Fair Value of Credit Default Swaps	(1)		$ (1)		(1)
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Average Remaining Maturity			1 year 2 months	2 years
Credit Index Product [Member] | B
Derivatives, Fair Value [Line Items]
Maximum Amount of Future Payments under Credit Default Swaps	625		$ 625		625
Estimated Fair Value of Credit Default Swaps	0		$ 0		$ 39
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Average Remaining Maturity			5 years 1 month		4 years 11 months
Credit Default Swap [Member] | Ba [Member]
Derivatives, Fair Value [Line Items]
Maximum Amount of Future Payments under Credit Default Swaps	60		$ 60		$ 60
Estimated Fair Value of Credit Default Swaps	1		$ 1		$ 0
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Average Remaining Maturity			2 years 2 months		3 years
Credit Default Swap [Member] | B
Derivatives, Fair Value [Line Items]
Maximum Amount of Future Payments under Credit Default Swaps	0		$ 0		$ 0
Estimated Fair Value of Credit Default Swaps	$ 0		$ 0		$ 0
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Average Remaining Maturity			0 years		0 years