Contingencies, Commitments and Guarantees (Contingencies - Narrative) (Details)	3 Months Ended		9 Months Ended		12 Months Ended
	Mar. 31, 2015 USD ($)	Mar. 31, 2014 USD ($)	Sep. 30, 2015 USD ($) Claims Plaintiffs	Sep. 30, 2014 Claims	Dec. 31, 2014 Claims
MetLife Home Loans LLC
Loss Contingencies
Litigation Settlement, Amount	$ (123,500,000)
Minimum
Loss Contingencies
The approximate amount of the aggregate range of reasonably possible losses in excess of amounts accrued for matters as to which an estimate can be made			$ 0
Maximum
Loss Contingencies
The approximate amount of the aggregate range of reasonably possible losses in excess of amounts accrued for matters as to which an estimate can be made			$ 425,000,000
Superfund Site Settlement Agreements
Loss Contingencies
Number of regulatory matters and other claims | Claims			2
Maximum estimate of aggregate costs to resolve matter			$ 1,000,000
Maximum estimate of costs for environmental testing			100,000
Superfund Site Settlement Agreements | Minimum
Loss Contingencies
Damages Sought			1,000,000
C-Mart, Inc. V. Metropolitan Life Insurance Company, Et Al | Maximum
Loss Contingencies
Loss Contingency, Estimate of Possible Loss			$ 23,000,000
Derivative Actions And Demands
Loss Contingencies
Number of plaintiffs | Plaintiffs			2
Asbestos Related Claims
Loss Contingencies
Asbestos-Related Claims | Claims			2,971	3,641	4,636
New York Licensing Inquiry | Department of Financial Services
Loss Contingencies
Litigation Settlement, Amount		$ (50,000,000)
New York Licensing Inquiry | New York County, District Attorney
Loss Contingencies
Litigation Settlement, Amount		$ (10,000,000)