Equity (Components of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period	$ 6,443	$ 11,058	$ 10,649	$ 5,104
OCI before reclassifications	728	(174)	(5,269)	9,288
Deferred income tax benefit (expense)	(411)	(85)	1,345	(3,143)
AOCI before reclassifications, net of income tax	6,760	10,799	6,725	11,249
Amounts reclassified from AOCI	194	302	269	(13)
Deferred income tax benefit (expense)	(63)	(109)	(103)	(10)
Amounts reclassified from AOCI, net of income tax	131	193	166	(23)
Balance, end of period	6,891	10,992	6,891	10,992
Unrealized Investment Gains (Losses), Net of Related Offsets
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period	11,761	13,909	15,159	8,183
OCI before reclassifications	962	(56)	(3,923)	9,126
Deferred income tax benefit (expense)	(340)	130	1,337	(2,851)
AOCI before reclassifications, net of income tax	12,383	13,983	12,573	14,458
Amounts reclassified from AOCI	(102)	(214)	(392)	(563)
Deferred income tax benefit (expense)	34	62	134	176
Amounts reclassified from AOCI, net of income tax	(68)	(152)	(258)	(387)
Balance, end of period	12,315	13,831	12,315	13,831
Unrealized Gains (Losses) on Derivatives
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period	1,102	476	1,076	231
OCI before reclassifications	102	118	(106)	614
Deferred income tax benefit (expense)	(47)	(49)	37	(210)
AOCI before reclassifications, net of income tax	1,157	545	1,007	635
Amounts reclassified from AOCI	239	471	490	337
Deferred income tax benefit (expense)	(77)	(158)	(178)	(114)
Amounts reclassified from AOCI, net of income tax	162	313	312	223
Balance, end of period	1,319	858	1,319	858
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period	(4,214)	(1,739)	(3,303)	(1,659)
OCI before reclassifications	(336)	(264)	(1,243)	(486)
Deferred income tax benefit (expense)	(24)	(157)	(28)	(71)
AOCI before reclassifications, net of income tax	(4,574)	(2,160)	(4,574)	(2,216)
Amounts reclassified from AOCI	0	0	0	77
Deferred income tax benefit (expense)	0	0	0	(27)
Amounts reclassified from AOCI, net of income tax	0	0	0	50
Balance, end of period	(4,574)	(2,160)	(4,574)	(2,160)
Defined Benefit Plans Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period	(2,206)	(1,588)	(2,283)	(1,651)
OCI before reclassifications	0	28	3	34
Deferred income tax benefit (expense)	0	(9)	(1)	(11)
AOCI before reclassifications, net of income tax	(2,206)	(1,569)	(2,281)	(1,628)
Amounts reclassified from AOCI	57	45	171	136
Deferred income tax benefit (expense)	(20)	(13)	(59)	(45)
Amounts reclassified from AOCI, net of income tax	37	32	112	91
Balance, end of period	(2,169)	(1,537)	(2,169)	(1,537)
MetLife Assurance Limited
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from AOCI	0	0	0	(314)
Deferred income tax benefit (expense)	0	0	0	80
Amounts reclassified from AOCI, net of income tax	0	0	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	0	0	(320)
Deferred income tax benefit (expense)	0	0	0	80
Amounts reclassified from AOCI, net of income tax	0	0	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	0	0	6
Deferred income tax benefit (expense)	0	0	0	0
Amounts reclassified from AOCI, net of income tax	0	0	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