Derivative Instruments and Hedging Activities - Notional and Fair Values of Derivative Instruments (Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Derivatives, Fair Value [Line Items]
Cumulative counterparty credit risk valuation adjustment	$ 4	$ 6
Notional or Contractual Amount	166,850	142,938
Derivative Assets, Gross Amount	773	1,494
Derivative Liabilities, Gross Amount	879	1,438
Derivative Asset, Netting Adjustment	(309)	(539)
Derivative Liability, Netting Adjustment	(355)	(336)
Derivative Assets	464	955
Derivative Liability	524	1,102
Cumulative credit risk valuation adjustment related to our credit quality (less than $1 million	1	1
Decrease in derivative assets due to CME Rulebook change	58
Decrease in derivative liabilities due to CME Rulebook change	348
Derivatives designated as accounting hedges
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	118,810	98,896
Derivative Assets, Gross Amount	155	717
Derivative Liabilities, Gross Amount	422	865
Derivatives designated as accounting hedges | Interest rate contracts
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	110,292	90,880
Derivative Assets, Gross Amount	154	446
Derivative Liabilities, Gross Amount	178	856
Derivatives designated as accounting hedges | Interest rate contracts | Fair value hedges
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	51,592	40,480
Derivative Assets, Gross Amount	124	295
Derivative Liabilities, Gross Amount	89	569
Derivatives designated as accounting hedges | Interest rate contracts | Cash flow hedges
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	58,700	50,400
Derivative Assets, Gross Amount	30	151
Derivative Liabilities, Gross Amount	89	287
Derivatives designated as accounting hedges | Foreign exchange contracts
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	8,518	8,016
Derivative Assets, Gross Amount	1	271
Derivative Liabilities, Gross Amount	244	9
Derivatives designated as accounting hedges | Foreign exchange contracts | Cash flow hedges
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	5,802	5,620
Derivative Assets, Gross Amount	0	108
Derivative Liabilities, Gross Amount	143	9
Derivatives designated as accounting hedges | Foreign exchange contracts | Net investment hedges
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	2,716	2,396
Derivative Assets, Gross Amount	1	163
Derivative Liabilities, Gross Amount	101	0
Derivatives not designated as accounting hedges
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	48,040	44,042
Derivative Assets, Gross Amount	618	777
Derivative Liabilities, Gross Amount	457	573
Derivatives not designated as accounting hedges | Interest rate contracts
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	46,985	42,275
Derivative Assets, Gross Amount	618	720
Derivative Liabilities, Gross Amount	451	559
Derivatives not designated as accounting hedges | Interest rate contracts | MSRs
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	1,491	1,696
Derivative Assets, Gross Amount	11	17
Derivative Liabilities, Gross Amount	2	21
Derivatives not designated as accounting hedges | Interest rate contracts | Customer accommodation
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	42,657	39,474
Derivative Assets, Gross Amount	571	670
Derivative Liabilities, Gross Amount	437	530
Derivatives not designated as accounting hedges | Interest rate contracts | Other interest rate exposures
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	2,837	1,105
Derivative Assets, Gross Amount	36	33
Derivative Liabilities, Gross Amount	12	8
Derivatives not designated as accounting hedges | Other contracts
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	1,055	1,767
Derivative Assets, Gross Amount	0	57
Derivative Liabilities, Gross Amount	$ 6	$ 14