Derivative instruments - Credit Derivatives, Protection Sold, Notional and Fair Value (Details) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
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	$ (397,460)	$ (480,679)
Protection sold credit derivatives and credit-related notes ratings/maturity profile - from 1-5 years	(1,189,282)	(1,515,091)
Protection sold credit derivatives and credit-related notes ratings/maturity profile - more than 5 years	(141,503)	(104,533)
Total notional amount	(1,728,245)	(2,100,303)
Fair value of receivables	28,316	46,444
Fair value of payables	(24,708)	(28,769)
Net fair value	3,608	17,675
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	(278,173)	(323,398)
Protection sold credit derivatives and credit-related notes ratings/maturity profile - from 1-5 years	(881,329)	(1,118,293)
Protection sold credit derivatives and credit-related notes ratings/maturity profile - more than 5 years	(101,523)	(79,486)
Total notional amount	(1,261,025)	(1,521,177)
Fair value of receivables	15,057	25,767
Fair value of payables	(6,870)	(6,314)
Net fair value	8,187	19,453
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	(119,287)	(157,281)
Protection sold credit derivatives and credit-related notes ratings/maturity profile - from 1-5 years	(307,953)	(396,798)
Protection sold credit derivatives and credit-related notes ratings/maturity profile - more than 5 years	(39,980)	(25,047)
Total notional amount	(467,220)	(579,126)
Fair value of receivables	13,259	20,677
Fair value of payables	(17,838)	(22,455)
Net fair value	$ (4,579)	$ (1,778)