v3.8.0.1
Investments (Equity Method Investments, Statement of Financial Position) (Details) - USD ($)
$ in Millions
Dec. 31, 2017
Dec. 31, 2016
Investments [Abstract]    
Total assets $ 62,292 $ 59,897
Total liabilities 15,225 14,787
Partners’ capital 47,067 45,110
Total liabilities and partners’ capital 62,292 59,897
Total liabilities and partners’ capital included above 5,515 5,135
Equity in limited partnership interests not included above 696 592
Carrying value $ 6,211 $ 5,727