Insurance (Insurance Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Insurance Liabilities [Line Items]
Insurance liabilities comprised of future policy benefits, policyholder account balances and other policy-related balances	$ 404,707	$ 387,002
U.S.
Insurance Liabilities [Line Items]
Insurance liabilities comprised of future policy benefits, policyholder account balances and other policy-related balances	150,327	141,641
Asia
Insurance Liabilities [Line Items]
Insurance liabilities comprised of future policy benefits, policyholder account balances and other policy-related balances	118,027	108,456
Latin America
Insurance Liabilities [Line Items]
Insurance liabilities comprised of future policy benefits, policyholder account balances and other policy-related balances	15,911	16,131
EMEA
Insurance Liabilities [Line Items]
Insurance liabilities comprised of future policy benefits, policyholder account balances and other policy-related balances	16,951	17,069
MetLife Holdings
Insurance Liabilities [Line Items]
Insurance liabilities comprised of future policy benefits, policyholder account balances and other policy-related balances	101,945	102,371
Corporate & Other
Insurance Liabilities [Line Items]
Insurance liabilities comprised of future policy benefits, policyholder account balances and other policy-related balances	$ 1,546	$ 1,334