Fair Value, Transfers Between Fair Value Levels (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Fair Value, Assets and Liabilities Measured on Recurring Basis Transfers Between Fair Value Levels [Line Items]
Total	$ 0	$ 0	$ 0	$ 0
Trading assets (excluding derivatives) [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis Transfers Between Fair Value Levels [Line Items]
Total	0	0	0	0
Available-for-sale securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis Transfers Between Fair Value Levels [Line Items]
Total	0	0	0	0
Mortgages held for sale [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis Transfers Between Fair Value Levels [Line Items]
Total	0	0	0	0
Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis Transfers Between Fair Value Levels [Line Items]
Total	0	0	0	0
Net derivative assets and liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis Transfers Between Fair Value Levels [Line Items]
Total	0	0	0	0
Short sale liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis Transfers Between Fair Value Levels [Line Items]
Total	0		0
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis Transfers Between Fair Value Levels [Line Items]
Transfer In	0	0	15	0
Transfer Out	0	0	(3)	(8)
Fair Value, Inputs, Level 1 [Member] | Trading assets (excluding derivatives) [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis Transfers Between Fair Value Levels [Line Items]
Transfer In	0	0	16	0
Transfer Out	0	0	(3)	0
Fair Value, Inputs, Level 1 [Member] | Available-for-sale securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis Transfers Between Fair Value Levels [Line Items]
Transfer In	0	0	0	0
Transfer Out	0	0	0	8
Fair Value, Inputs, Level 1 [Member] | Mortgages held for sale [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis Transfers Between Fair Value Levels [Line Items]
Transfer In	0	0	0	0
Transfer Out	0	0	0	0
Fair Value, Inputs, Level 1 [Member] | Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis Transfers Between Fair Value Levels [Line Items]
Transfer In	0	0	0	0
Transfer Out	0	0	0	0
Fair Value, Inputs, Level 1 [Member] | Net derivative assets and liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis Transfers Between Fair Value Levels [Line Items]
Transfer In	0	0	0	0
Transfer Out	0	0	0	0
Fair Value, Inputs, Level 1 [Member] | Short sale liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis Transfers Between Fair Value Levels [Line Items]
Transfer In	0		(1)
Transfer Out	0		0
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis Transfers Between Fair Value Levels [Line Items]
Transfer In	511	101	674	229
Transfer Out	(53)	(459)	(98)	(642)
Fair Value, Inputs, Level 2 [Member] | Trading assets (excluding derivatives) [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis Transfers Between Fair Value Levels [Line Items]
Transfer In	83	38	93	40
Transfer Out	0	0	(16)	(28)
Fair Value, Inputs, Level 2 [Member] | Available-for-sale securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis Transfers Between Fair Value Levels [Line Items]
Transfer In	24	97	76	105
Transfer Out	0	(53)	0	(148)
Fair Value, Inputs, Level 2 [Member] | Mortgages held for sale [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis Transfers Between Fair Value Levels [Line Items]
Transfer In	386	98	453	122
Transfer Out	(53)	(139)	(95)	(196)
Fair Value, Inputs, Level 2 [Member] | Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis Transfers Between Fair Value Levels [Line Items]
Transfer In	0	0	0	49
Transfer Out	0	(270)	0	(270)
Fair Value, Inputs, Level 2 [Member] | Net derivative assets and liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis Transfers Between Fair Value Levels [Line Items]
Transfer In	18	(132)	52	(87)
Transfer Out	0	3	12	0
Fair Value, Inputs, Level 2 [Member] | Short sale liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis Transfers Between Fair Value Levels [Line Items]
Transfer In	0		0
Transfer Out	0		1
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis Transfers Between Fair Value Levels [Line Items]
Transfer In	53	459	84	642
Transfer Out	(511)	(101)	(672)	(221)
Fair Value, Inputs, Level 3 [Member] | Trading assets (excluding derivatives) [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis Transfers Between Fair Value Levels [Line Items]
Transfer In	0	0	1	28
Transfer Out	(83)	(38)	(91)	(40)
Fair Value, Inputs, Level 3 [Member] | Available-for-sale securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis Transfers Between Fair Value Levels [Line Items]
Fair Value Level, Transfer Out, Amount Except For	640
Transfer In	0	53	0	148
Transfer Out	(24)	(97)	(76)	(97)
Fair Value, Inputs, Level 3 [Member] | Mortgages held for sale [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis Transfers Between Fair Value Levels [Line Items]
Transfer In	53	139	95	196
Transfer Out	(386)	(98)	(453)	(122)
Fair Value, Inputs, Level 3 [Member] | Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis Transfers Between Fair Value Levels [Line Items]
Transfer In	0	270	0	270
Transfer Out	0	0	0	(49)
Fair Value, Inputs, Level 3 [Member] | Net derivative assets and liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis Transfers Between Fair Value Levels [Line Items]
Transfer In	0	(3)	(12)	0
Transfer Out	(18)	$ 132	(52)	$ 87
Fair Value, Inputs, Level 3 [Member] | Short sale liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis Transfers Between Fair Value Levels [Line Items]
Transfer In	0		0
Transfer Out	$ 0		$ 0