Derivative Instruments - Credit Derivatives, Protection Sold, Notional and Fair Value (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Protection sold credit derivatives and credit related notes ratings/maturity profile
Protection sold credit derivatives and credit related notes ratings/maturity profile - less than 1 year	$ (170,033)	$ (232,680)
Protection sold credit derivatives and credit-related notes ratings/maturity profile - from 1-5 years	(511,587)	(453,851)
Protection sold credit derivatives and credit-related notes ratings/maturity profile - more than 5 years	(103,521)	(57,868)
Total notional amount	(785,141)	(744,399)
Fair value of receivables	16,380	15,923
Fair value of payables	(6,378)	(6,447)
Net fair value	10,002	9,476
Investment-grade
Protection sold credit derivatives and credit related notes ratings/maturity profile
Protection sold credit derivatives and credit related notes ratings/maturity profile - less than 1 year	(116,930)	(159,286)
Protection sold credit derivatives and credit-related notes ratings/maturity profile - from 1-5 years	(364,470)	(319,726)
Protection sold credit derivatives and credit-related notes ratings/maturity profile - more than 5 years	(71,226)	(39,429)
Total notional amount	(552,626)	(518,441)
Fair value of receivables	8,043	8,516
Fair value of payables	(1,859)	(1,134)
Net fair value	6,184	7,382
Noninvestment-grade
Protection sold credit derivatives and credit related notes ratings/maturity profile
Protection sold credit derivatives and credit related notes ratings/maturity profile - less than 1 year	(53,103)	(73,394)
Protection sold credit derivatives and credit-related notes ratings/maturity profile - from 1-5 years	(147,117)	(134,125)
Protection sold credit derivatives and credit-related notes ratings/maturity profile - more than 5 years	(32,295)	(18,439)
Total notional amount	(232,515)	(225,958)
Fair value of receivables	8,337	7,407
Fair value of payables	(4,519)	(5,313)
Net fair value	$ 3,818	$ 2,094