Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Investments:
Amortized cost of fixed maturity securities available-for-sale	$ 340,870	$ 329,811
Fixed maturity securities relating to variable interest entities	374,266	350,271
Cost of equity securities available-for-sale	2,838	3,208
Actively traded securities	659	473
Fair value option and trading securities relating to variable interest entities	16,348	18,268
Mortgage loans:
Valuation allowances for held-for-investment	347	481
Mortgage loans, at estimated fair value, relating to variable interest entities	56,592	56,915
Mortgage loans held-for-sale under fair value option	49	10,716
Real estate and real estate joint ventures relating to variable interest entities	9,918	8,563
Other limited partnership interests relating to variable interest entities	6,688	6,378
Other invested assets relating to variable interest entities	21,145	23,581
Cash and cash equivalents relating to variable interest entities	15,738	10,461
Accrued investment income relating to variable interest entities	4,374	4,344
Premiums, reinsurance and other receivables relating to variable interest entities	21,634	22,481
Other assets relating to variable interest entities	7,876	7,984
Liabilities
Long-term debt, at estimated fair value, relating to variable interest entities	19,062	23,692
Other liabilities relating to variable interest entities	22,492	30,914
Other liabilities under fair value option	0	7,626
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	$ 2,100.00	$ 2,100.00
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	3,000,000,000	3,000,000,000
Common stock, shares issued	1,094,880,623	1,061,150,915
Common stock, shares outstanding	1,091,686,736	1,057,957,028
Treasury stock, shares	3,193,887	3,193,887
Variable interest entities
Investments:
Fixed maturity securities relating to variable interest entities	3,378	3,225
Fair value option and trading securities relating to variable interest entities	112	280
Mortgage loans:
Mortgage loans, at estimated fair value, relating to variable interest entities	2,715	3,187
Real estate and real estate joint ventures relating to variable interest entities	10	15
Other limited partnership interests relating to variable interest entities	274	259
Other invested assets relating to variable interest entities	81	98
Cash and cash equivalents relating to variable interest entities	99	176
Accrued investment income relating to variable interest entities	13	16
Premiums, reinsurance and other receivables relating to variable interest entities	5	12
Other assets relating to variable interest entities	5	5
Liabilities
Long-term debt, at estimated fair value, relating to variable interest entities	2,527	3,068
Other liabilities relating to variable interest entities	$ 40	$ 60