Insurance (Insurance Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Insurance Liabilities [Line Items]
Insurance liabilities comprised of future policy benefits, policyholder account balances and other policy-related balances	$ 420,945	$ 428,933
U.S.
Insurance Liabilities [Line Items]
Insurance liabilities comprised of future policy benefits, policyholder account balances and other policy-related balances	162,999	162,524
Asia
Insurance Liabilities [Line Items]
Insurance liabilities comprised of future policy benefits, policyholder account balances and other policy-related balances	125,839	126,912
Latin America
Insurance Liabilities [Line Items]
Insurance liabilities comprised of future policy benefits, policyholder account balances and other policy-related balances	15,564	16,849
EMEA
Insurance Liabilities [Line Items]
Insurance liabilities comprised of future policy benefits, policyholder account balances and other policy-related balances	13,031	17,252
MetLife Holdings
Insurance Liabilities [Line Items]
Insurance liabilities comprised of future policy benefits, policyholder account balances and other policy-related balances	102,291	103,937
Corporate & Other
Insurance Liabilities [Line Items]
Insurance liabilities comprised of future policy benefits, policyholder account balances and other policy-related balances	$ 1,221	$ 1,459