Consolidated Balance Sheets (Unaudited) (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Investments:
Amortized cost of fixed maturity securities available-for-sale	$ 330,900	$ 340,870
Fixed maturity securities relating to variable interest entities	348,787	374,266
Cost of equity securities available-for-sale	2,978	2,838
Actively traded securities	636	659
Fair value option and trading securities relating to variable interest entities	16,646	16,348
Mortgage loans:
Mortgage loans valuation allowances	326	347
Mortgage loans, at estimated fair value, relating to variable interest entities	57,508	56,592
Mortgage loans held-for-sale under fair value option	225	414
Policy loans	11,782	11,884
Real estate and real estate joint ventures relating to variable interest entities	10,053	9,918
Other limited partnership interests relating to variable interest entities	7,253	6,688
Short-term investments	12,664	16,906
Other invested assets relating to variable interest entities	16,766	21,145
Cash and cash equivalents relating to variable interest entities	11,376	15,738
Accrued investment income relating to variable interest entities	4,519	4,374
Premiums, reinsurance and other receivables relating to variable interest entities	23,473	21,634
Deferred policy acquisition costs and value of business acquired relating to variable interest entities	25,639	24,761
Other assets relating to variable interest entities	7,952	7,876
Separate account assets	255,250	235,393
Liabilities
Future policy benefits relating to variable interest entities	186,528	192,351
Policyholder account balances	214,512	225,821
Other policy-related balances relating to variable interest entities	15,530	15,463
Long-term debt, at estimated fair value, relating to variable interest entities	18,252	19,062
Other liabilities relating to variable interest entities	22,902	22,492
Separate account liabilities	255,250	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	1,124,039,249	1,094,880,623
Common stock, shares outstanding	1,120,845,362	1,091,686,736
Treasury stock, shares	3,193,887	3,193,887
Mortgage Loans Held-for-sale [Member]
Mortgage loans:
Mortgage loans held-for-sale under fair value option	0	49
Variable interest entities [Member]
Investments:
Fixed maturity securities relating to variable interest entities	3,940	3,378
Fair value option and trading securities relating to variable interest entities	91	112
Mortgage loans:
Mortgage loans, at estimated fair value, relating to variable interest entities	2,119	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	151	274
Short-term investments	6	0
Other invested assets relating to variable interest entities	78	81
Cash and cash equivalents relating to variable interest entities	64	99
Accrued investment income relating to variable interest entities	27	13
Premiums, reinsurance and other receivables relating to variable interest entities	19	5
Deferred policy acquisition costs and value of business acquired relating to variable interest entities	251	0
Other assets relating to variable interest entities	133	5
Separate account assets	984	0
Liabilities
Future policy benefits relating to variable interest entities	468	0
Policyholder account balances	55	0
Other policy-related balances relating to variable interest entities	124	0
Long-term debt, at estimated fair value, relating to variable interest entities	1,946	2,527
Other liabilities relating to variable interest entities	89	40
Separate account liabilities	$ 984	$ 0