Equity (Components of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period	$ 11,529	$ 8,215	$ 10,649	$ 5,104
OCI before reclassifications	(7,140)	4,506	(5,997)	9,462
Deferred income tax benefit (expense)	2,336	(1,333)	1,756	(3,058)
AOCI before reclassifications, net of income tax	6,725	11,388	6,408	11,508
Amounts reclassified from AOCI	(423)	(133)	75	(315)
Deferred income tax benefit (expense)	141	37	(40)	99
Amounts reclassified from AOCI, net of income tax	(282)	(96)	35	(216)
Balance, end of period	6,443	11,058	6,443	11,058
Unrealized Investment Gains (Losses), Net of Related Offsets
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period	16,206	11,276	15,159	8,183
OCI before reclassifications	(6,511)	4,330	(4,885)	9,182
Deferred income tax benefit (expense)	2,178	(1,336)	1,677	(2,981)
AOCI before reclassifications, net of income tax	11,873	14,270	11,951	14,384
Amounts reclassified from AOCI	(177)	(176)	(290)	(349)
Deferred income tax benefit (expense)	65	55	100	114
Amounts reclassified from AOCI, net of income tax	(112)	(121)	(190)	(235)
Balance, end of period	11,761	13,909	11,761	13,909
Unrealized Gains (Losses) on Derivatives
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period	1,555	404	1,076	231
OCI before reclassifications	(395)	175	(208)	496
Deferred income tax benefit (expense)	150	(48)	84	(161)
AOCI before reclassifications, net of income tax	1,310	531	952	566
Amounts reclassified from AOCI	(303)	(80)	251	(134)
Deferred income tax benefit (expense)	95	25	(101)	44
Amounts reclassified from AOCI, net of income tax	(208)	(55)	150	(90)
Balance, end of period	1,102	476	1,102	476
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period	(3,986)	(1,843)	(3,303)	(1,659)
OCI before reclassifications	(237)	(5)	(907)	(222)
Deferred income tax benefit (expense)	9	53	(4)	86
AOCI before reclassifications, net of income tax	(4,214)	(1,795)	(4,214)	(1,795)
Amounts reclassified from AOCI	0	77	0	77
Deferred income tax benefit (expense)	0	(27)	0	(27)
Amounts reclassified from AOCI, net of income tax	0	50	0	50
Balance, end of period	(4,214)	(1,739)	(4,214)	(1,739)
Defined Benefit Plans Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period	(2,246)	(1,622)	(2,283)	(1,651)
OCI before reclassifications	3	6	3	6
Deferred income tax benefit (expense)	(1)	(2)	(1)	(2)
AOCI before reclassifications, net of income tax	(2,244)	(1,618)	(2,281)	(1,647)
Amounts reclassified from AOCI	57	46	114	91
Deferred income tax benefit (expense)	(19)	(16)	(39)	(32)
Amounts reclassified from AOCI, net of income tax	38	30	75	59
Balance, end of period	(2,206)	(1,588)	(2,206)	(1,588)
MetLife Assurance Limited
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from AOCI	0	(314)	0	(314)
Deferred income tax benefit (expense)	0	80	0	80
Amounts reclassified from AOCI, net of income tax	0	(234)	0	(234)
MetLife Assurance Limited | Unrealized Investment Gains (Losses), Net of Related Offsets
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from AOCI	0	(320)	0	(320)
Deferred income tax benefit (expense)	0	80	0	80
Amounts reclassified from AOCI, net of income tax	0	(240)	0	(240)
MetLife Assurance Limited | Unrealized Gains (Losses) on Derivatives
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from AOCI	0	0	0	0
Deferred income tax benefit (expense)	0	0	0	0
Amounts reclassified from AOCI, net of income tax	0	0	0	0
MetLife Assurance Limited | Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from AOCI	0	6	0	6
Deferred income tax benefit (expense)	0	0	0	0
Amounts reclassified from AOCI, net of income tax	0	6	0	6
MetLife Assurance Limited | Defined Benefit Plans Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from AOCI	0	0	0	0
Deferred income tax benefit (expense)	0	0	0	0
Amounts reclassified from AOCI, net of income tax	$ 0	$ 0	$ 0	$ 0