Fair Value, Assets Recorded at Fair Value on a Nonrecurring Basis Level 3 Valuation Techniques and Significant Unobservable Inputs (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Mortgages held for sale	$ 21,539	$ 15,565
Minimum [Member] | Mortgages held for sale [Member] | Discounted cash flow [Member]
Fair Value Inputs [Abstract]
Default rate	0.60%	0.40%
Discount rate	1.10%	1.10%
Loss severity	0.00%	0.10%
Prepayment rate	2.00%	2.00%
Minimum [Member] | Mortgages held for sale [Member] | Market comparable pricing [Member]
Fair Value Inputs [Abstract]
Comparability adjustment	(65.80%)	(93.00%)
Maximum [Member] | Mortgages held for sale [Member] | Discounted cash flow [Member]
Fair Value Inputs [Abstract]
Default rate	14.00%	15.00%
Discount rate	6.30%	7.70%
Loss severity	24.40%	26.40%
Prepayment rate	18.50%	15.50%
Maximum [Member] | Mortgages held for sale [Member] | Market comparable pricing [Member]
Fair Value Inputs [Abstract]
Comparability adjustment	2.70%	10.00%
Weighted Average [Member] | Mortgages held for sale [Member] | Discounted cash flow [Member]
Fair Value Inputs [Abstract]
Default rate	2.80%	2.60%
Discount rate	4.60%	5.20%
Loss severity	14.40%	18.30%
Prepayment rate	8.40%	8.10%
Weighted Average [Member] | Mortgages held for sale [Member] | Market comparable pricing [Member]
Fair Value Inputs [Abstract]
Comparability adjustment	(27.20%)	(30.00%)
Nonrecurring [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Mortgages held for sale	$ 3,100	$ 3,295
Nonrecurring [Member] | Minimum [Member] | Market comparable pricing [Member] | Private Equity Funds [Member]
Fair Value Inputs [Abstract]
Comparability adjustment	0.00%	6.00%
Nonrecurring [Member] | Minimum [Member] | Market comparable pricing [Member] | Other Assets: Nonmarketable Equity Investments [Member]
Fair Value Inputs [Abstract]
Comparability adjustment	4.80%
Nonrecurring [Member] | Minimum [Member] | Residential [Member] | Mortgages held for sale [Member] | Discounted cash flow [Member]
Fair Value Inputs [Abstract]
Default rate	0.30%	0.90%
Discount rate	1.50%	1.50%
Loss severity	0.90%	0.00%
Prepayment rate	1.30%	2.00%
Nonrecurring [Member] | Maximum [Member] | Market comparable pricing [Member] | Private Equity Funds [Member]
Fair Value Inputs [Abstract]
Comparability adjustment	0.00%	6.00%
Nonrecurring [Member] | Maximum [Member] | Market comparable pricing [Member] | Other Assets: Nonmarketable Equity Investments [Member]
Fair Value Inputs [Abstract]
Comparability adjustment	8.00%
Nonrecurring [Member] | Maximum [Member] | Residential [Member] | Mortgages held for sale [Member] | Discounted cash flow [Member]
Fair Value Inputs [Abstract]
Default rate	7.00%	3.80%
Discount rate	8.50%	8.50%
Loss severity	32.70%	29.80%
Prepayment rate	100.00%	100.00%
Nonrecurring [Member] | Weighted Average [Member] | Market comparable pricing [Member] | Private Equity Funds [Member]
Fair Value Inputs [Abstract]
Comparability adjustment	0.00%	6.00%
Nonrecurring [Member] | Weighted Average [Member] | Market comparable pricing [Member] | Other Assets: Nonmarketable Equity Investments [Member]
Fair Value Inputs [Abstract]
Comparability adjustment	6.60%
Nonrecurring [Member] | Weighted Average [Member] | Residential [Member] | Mortgages held for sale [Member] | Discounted cash flow [Member]
Fair Value Inputs [Abstract]
Default rate	3.30%	2.10%
Discount rate	3.50%	3.60%
Loss severity	3.40%	3.80%
Prepayment rate	58.80%	65.50%
Fair Value, Inputs, Level 3 [Member] | Nonrecurring [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Mortgages held for sale	$ 955	$ 1,098
Other assets: private equity fund investments	0	171
Insignificant level 3 assets	191	294
Total	1,367	1,563
Fair Value Inputs [Abstract]
Other Assets Nonmarketable Equity Investments, Fair Value Disclosure	221
Fair Value, Inputs, Level 3 [Member] | Nonrecurring [Member] | Residential [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Mortgages held for sale	$ 955	$ 1,098