Consolidated Balance Sheets (Unaudited) (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Investments:
Amortized cost of fixed maturity securities available-for-sale	$ 335,626	$ 340,870
Fixed maturity securities relating to variable interest entities	356,514	374,266
Cost of equity securities available-for-sale	2,922	2,838
Actively traded securities	744	659
Fair value option and trading securities relating to variable interest entities	16,110	16,348
Mortgage loans:
Mortgage loans valuation allowances	302	347
Mortgage loans, at estimated fair value, relating to variable interest entities	55,636	56,592
Mortgage loans held-for-sale under fair value option	0	49
Policy loans	11,722	11,884
Real estate and real estate joint ventures relating to variable interest entities	9,886	9,918
Other limited partnership interests relating to variable interest entities	7,197	6,688
Short-term investments	12,990	16,906
Other invested assets relating to variable interest entities	17,920	21,145
Cash and cash equivalents relating to variable interest entities	9,184	15,738
Accrued investment income relating to variable interest entities	4,357	4,374
Premiums, reinsurance and other receivables relating to variable interest entities	23,283	21,634
Deferred policy acquisition costs and value of business acquired relating to variable interest entities	24,782	24,761
Other assets relating to variable interest entities	7,830	7,876
Separate account assets	245,573	235,393
Liabilities
Future policy benefits relating to variable interest entities	184,697	192,351
Policyholder account balances	215,195	225,821
Other policy-related balances relating to variable interest entities	15,279	15,463
Long-term debt, at estimated fair value, relating to variable interest entities	18,577	19,062
Other liabilities relating to variable interest entities	25,331	22,492
Separate account liabilities	245,573	235,393
MetLife, Inc.'s stockholders' equity:
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	200,000,000	200,000,000
Preferred stock, shares issued	84,000,000	84,000,000
Preferred stock, shares outstanding	84,000,000	84,000,000
Preferred stock, aggregate liquidation preference	$ 2,100	$ 2,100
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	3,000,000,000	3,000,000,000
Common stock, shares issued	1,099,795,436	1,094,880,623
Common stock, shares outstanding	1,096,601,549	1,091,686,736
Treasury stock, shares	3,193,887	3,193,887
Variable interest entities [Member]
Investments:
Fixed maturity securities relating to variable interest entities	4,064	3,378
Fair value option and trading securities relating to variable interest entities	92	112
Mortgage loans:
Mortgage loans, at estimated fair value, relating to variable interest entities	2,316	2,715
Policy loans	3	0
Real estate and real estate joint ventures relating to variable interest entities	9	10
Other limited partnership interests relating to variable interest entities	159	274
Short-term investments	13	0
Other invested assets relating to variable interest entities	78	81
Cash and cash equivalents relating to variable interest entities	54	99
Accrued investment income relating to variable interest entities	26	13
Premiums, reinsurance and other receivables relating to variable interest entities	16	5
Deferred policy acquisition costs and value of business acquired relating to variable interest entities	265	0
Other assets relating to variable interest entities	142	5
Separate account assets	1,096	0
Liabilities
Future policy benefits relating to variable interest entities	458	0
Policyholder account balances	66	0
Other policy-related balances relating to variable interest entities	129	0
Long-term debt, at estimated fair value, relating to variable interest entities	2,126	2,527
Other liabilities relating to variable interest entities	90	40
Separate account liabilities	$ 1,096	$ 0