v3.8.0.1
Investments (Commercial Mortgage and Other Loans) (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Commercial Mortgage and Other Loans [Line Items]    
Total commercial mortgage and agricultural property loans by property type $ 55,287 $ 51,985
Other loans 864 900
Total commercial mortgage and other loans [1] $ 56,045 $ 52,779
% of Total 100.00% 100.00%
Net carrying value of commercial loans held for sale $ 593 $ 519
Commercial Mortgage Loans    
Commercial Mortgage and Other Loans [Line Items]    
Total commercial mortgage and agricultural property loans by property type $ 52,084 $ 49,027
% of Total 94.20% 94.30%
Commercial mortgage and agricultural property loans    
Commercial Mortgage and Other Loans [Line Items]    
Valuation allowance, Commercial mortgage and agricultural property loans $ (100) $ (98)
Total net loans 55,187 51,887
Uncollateralized loans    
Commercial Mortgage and Other Loans [Line Items]    
Other loans 663 638
Residential property loans    
Commercial Mortgage and Other Loans [Line Items]    
Other loans 196 252
Other collateralized loans    
Commercial Mortgage and Other Loans [Line Items]    
Other loans 5 10
Other loans    
Commercial Mortgage and Other Loans [Line Items]    
Total net loans 858 892
Valuation allowance, Other loans (6) (8)
Office    
Commercial Mortgage and Other Loans [Line Items]    
Total commercial mortgage and agricultural property loans by property type $ 12,670 $ 12,424
% of Total 22.90% 23.90%
Retail    
Commercial Mortgage and Other Loans [Line Items]    
Total commercial mortgage and agricultural property loans by property type $ 8,543 $ 8,555
% of Total 15.50% 16.50%
Apartment/Multi-Family    
Commercial Mortgage and Other Loans [Line Items]    
Total commercial mortgage and agricultural property loans by property type $ 15,465 $ 13,733
% of Total 28.00% 26.40%
Industrial    
Commercial Mortgage and Other Loans [Line Items]    
Total commercial mortgage and agricultural property loans by property type $ 9,451 $ 8,075
% of Total 17.10% 15.50%
Hospitality    
Commercial Mortgage and Other Loans [Line Items]    
Total commercial mortgage and agricultural property loans by property type $ 2,067 $ 2,274
% of Total 3.70% 4.40%
Other    
Commercial Mortgage and Other Loans [Line Items]    
Total commercial mortgage and agricultural property loans by property type $ 3,888 $ 3,966
% of Total 7.00% 7.60%
Agricultural property loans    
Commercial Mortgage and Other Loans [Line Items]    
Total commercial mortgage and agricultural property loans by property type $ 3,203 $ 2,958
% of Total 5.80% 5.70%
[1] See Note 5 for details of balances associated with variable interest entities.