Fair Value Measurements (Details 4) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012
Discount [Member] | Nonrecurring [Member]
Quantitative Information about Level 3 Fair Value Measurements
Percentage of significant unobservable input weighted-average	0.31%
Fair Value, Inputs, Level 3 [Member] | Recurring [Member]
Quantitative Information about Level 3 Fair Value Measurements
Other investment	$ 216
Other investments - principal investments - direct, Valuation Techniques	Individualized analysis of the condition of each investment
Fair Value, Inputs, Level 3 [Member] | Nonrecurring [Member]
Quantitative Information about Level 3 Fair Value Measurements
Impaired loans	(101)
Goodwill	917
Mortgage servicing assets	226
Impaired loans, Valuation Techniques	Fair value of underlying collateral
Goodwill, Valuation Techniques	Discounted cash flow and market data
Mortgage servicing assets, Valuation Techniques	Discounted cash flow
Fair Value, Inputs, Level 3 [Member] | Debt Securities [Member] | Recurring [Member]
Quantitative Information about Level 3 Fair Value Measurements
Other investment	0
Fair Value, Inputs, Level 3 [Member] | Equity Securities [Member] | Recurring [Member]
Quantitative Information about Level 3 Fair Value Measurements
Other investment	0
Fair Value, Inputs, Level 3 [Member] | EBITDA multiple [Member] | Recurring [Member]
Quantitative Information about Level 3 Fair Value Measurements
Percentage of significant unobservable input weighted-average	5.90%
Fair Value, Inputs, Level 3 [Member] | EBITDA multiple (where applicable) [Member] | Recurring [Member]
Quantitative Information about Level 3 Fair Value Measurements
Percentage of significant unobservable input weighted-average	4.80%
Fair Value, Inputs, Level 3 [Member] | Revenue multiple (where applicable) [Member] | Recurring [Member]
Quantitative Information about Level 3 Fair Value Measurements
Percentage of significant unobservable input weighted-average	0.70%
Fair Value, Inputs, Level 3 [Member] | Earnings multiple of peers [Member] | Nonrecurring [Member]
Quantitative Information about Level 3 Fair Value Measurements
Significant unobservable input weighted-average	10.01
Fair Value, Inputs, Level 3 [Member] | Equity multiple of peers [Member] | Nonrecurring [Member]
Quantitative Information about Level 3 Fair Value Measurements
Significant unobservable input weighted-average	1.27
Fair Value, Inputs, Level 3 [Member] | Control premium [Member] | Nonrecurring [Member]
Quantitative Information about Level 3 Fair Value Measurements
Percentage of significant unobservable input weighted-average	32.00%
Fair Value, Inputs, Level 3 [Member] | Weighted-average cost of capital [Member] | Nonrecurring [Member]
Quantitative Information about Level 3 Fair Value Measurements
Percentage of significant unobservable input weighted-average	15.00%
Fair Value, Inputs, Level 3 [Member] | Prepayment speed [Member] | Nonrecurring [Member]
Quantitative Information about Level 3 Fair Value Measurements
Percentage of significant unobservable input weighted-average	12.60%
Fair Value, Inputs, Level 3 [Member] | Expected credit losses [Member] | Nonrecurring [Member]
Quantitative Information about Level 3 Fair Value Measurements
Percentage of significant unobservable input weighted-average	2.51%
Fair Value, Inputs, Level 3 [Member] | Residual cash flows discount rate [Member] | Nonrecurring [Member]
Quantitative Information about Level 3 Fair Value Measurements
Percentage of significant unobservable input weighted-average	9.50%
Fair Value, Inputs, Level 3 [Member] | Value assigned to escrow funds [Member] | Nonrecurring [Member]
Quantitative Information about Level 3 Fair Value Measurements
Percentage of significant unobservable input weighted-average	2.00%
Fair Value, Inputs, Level 3 [Member] | Servicing Cost [Member] | Nonrecurring [Member]
Quantitative Information about Level 3 Fair Value Measurements
Mortgage servicing assets	2,548
Fair Value, Inputs, Level 3 [Member] | Loan assumption rate [Member] | Nonrecurring [Member]
Quantitative Information about Level 3 Fair Value Measurements
Percentage of significant unobservable input weighted-average	2.14%
Fair Value, Inputs, Level 3 [Member] | Percentage late [Member] | Nonrecurring [Member]
Quantitative Information about Level 3 Fair Value Measurements
Percentage of significant unobservable input weighted-average	0.22%
Minimum [Member] | Discount [Member] | Nonrecurring [Member]
Quantitative Information about Level 3 Fair Value Measurements
Percentage of significant unobservable input weighted-average	0.00%
Minimum [Member] | Fair Value, Inputs, Level 3 [Member] | EBITDA multiple [Member] | Recurring [Member]
Quantitative Information about Level 3 Fair Value Measurements
Percentage of significant unobservable input weighted-average	5.30%
Minimum [Member] | Fair Value, Inputs, Level 3 [Member] | EBITDA multiple (where applicable) [Member] | Recurring [Member]
Quantitative Information about Level 3 Fair Value Measurements
Percentage of significant unobservable input weighted-average	5.50%
Minimum [Member] | Fair Value, Inputs, Level 3 [Member] | Revenue multiple (where applicable) [Member] | Recurring [Member]
Quantitative Information about Level 3 Fair Value Measurements
Percentage of significant unobservable input weighted-average	0.20%
Minimum [Member] | Fair Value, Inputs, Level 3 [Member] | Earnings multiple of peers [Member] | Nonrecurring [Member]
Quantitative Information about Level 3 Fair Value Measurements
Significant unobservable input weighted-average	8.30
Minimum [Member] | Fair Value, Inputs, Level 3 [Member] | Equity multiple of peers [Member] | Nonrecurring [Member]
Quantitative Information about Level 3 Fair Value Measurements
Significant unobservable input weighted-average	1.21
Minimum [Member] | Fair Value, Inputs, Level 3 [Member] | Prepayment speed [Member] | Nonrecurring [Member]
Quantitative Information about Level 3 Fair Value Measurements
Percentage of significant unobservable input weighted-average	0.00%
Minimum [Member] | Fair Value, Inputs, Level 3 [Member] | Expected credit losses [Member] | Nonrecurring [Member]
Quantitative Information about Level 3 Fair Value Measurements
Percentage of significant unobservable input weighted-average	2.00%
Minimum [Member] | Fair Value, Inputs, Level 3 [Member] | Residual cash flows discount rate [Member] | Nonrecurring [Member]
Quantitative Information about Level 3 Fair Value Measurements
Percentage of significant unobservable input weighted-average	7.00%
Minimum [Member] | Fair Value, Inputs, Level 3 [Member] | Value assigned to escrow funds [Member] | Nonrecurring [Member]
Quantitative Information about Level 3 Fair Value Measurements
Percentage of significant unobservable input weighted-average	0.75%
Minimum [Member] | Fair Value, Inputs, Level 3 [Member] | Servicing Cost [Member] | Nonrecurring [Member]
Quantitative Information about Level 3 Fair Value Measurements
Mortgage servicing assets	700
Minimum [Member] | Fair Value, Inputs, Level 3 [Member] | Loan assumption rate [Member] | Nonrecurring [Member]
Quantitative Information about Level 3 Fair Value Measurements
Percentage of significant unobservable input weighted-average	0.00%
Minimum [Member] | Fair Value, Inputs, Level 3 [Member] | Percentage late [Member] | Nonrecurring [Member]
Quantitative Information about Level 3 Fair Value Measurements
Significant unobservable input weighted-average	0.0000
Maximum [Member] | Discount [Member] | Nonrecurring [Member]
Quantitative Information about Level 3 Fair Value Measurements
Percentage of significant unobservable input weighted-average	100.00%
Maximum [Member] | Fair Value, Inputs, Level 3 [Member] | EBITDA multiple [Member] | Recurring [Member]
Quantitative Information about Level 3 Fair Value Measurements
Percentage of significant unobservable input weighted-average	6.50%
Maximum [Member] | Fair Value, Inputs, Level 3 [Member] | EBITDA multiple (where applicable) [Member] | Recurring [Member]
Quantitative Information about Level 3 Fair Value Measurements
Percentage of significant unobservable input weighted-average	12.00%
Maximum [Member] | Fair Value, Inputs, Level 3 [Member] | Revenue multiple (where applicable) [Member] | Recurring [Member]
Quantitative Information about Level 3 Fair Value Measurements
Percentage of significant unobservable input weighted-average	4.70%
Maximum [Member] | Fair Value, Inputs, Level 3 [Member] | Earnings multiple of peers [Member] | Nonrecurring [Member]
Quantitative Information about Level 3 Fair Value Measurements
Significant unobservable input weighted-average	11.90
Maximum [Member] | Fair Value, Inputs, Level 3 [Member] | Equity multiple of peers [Member] | Nonrecurring [Member]
Quantitative Information about Level 3 Fair Value Measurements
Significant unobservable input weighted-average	1.32
Maximum [Member] | Fair Value, Inputs, Level 3 [Member] | Prepayment speed [Member] | Nonrecurring [Member]
Quantitative Information about Level 3 Fair Value Measurements
Percentage of significant unobservable input weighted-average	25.00%
Maximum [Member] | Fair Value, Inputs, Level 3 [Member] | Expected credit losses [Member] | Nonrecurring [Member]
Quantitative Information about Level 3 Fair Value Measurements
Percentage of significant unobservable input weighted-average	3.00%
Maximum [Member] | Fair Value, Inputs, Level 3 [Member] | Residual cash flows discount rate [Member] | Nonrecurring [Member]
Quantitative Information about Level 3 Fair Value Measurements
Percentage of significant unobservable input weighted-average	15.00%
Maximum [Member] | Fair Value, Inputs, Level 3 [Member] | Value assigned to escrow funds [Member] | Nonrecurring [Member]
Quantitative Information about Level 3 Fair Value Measurements
Percentage of significant unobservable input weighted-average	3.75%
Maximum [Member] | Fair Value, Inputs, Level 3 [Member] | Servicing Cost [Member] | Nonrecurring [Member]
Quantitative Information about Level 3 Fair Value Measurements
Mortgage servicing assets	$ 16,000
Maximum [Member] | Fair Value, Inputs, Level 3 [Member] | Loan assumption rate [Member] | Nonrecurring [Member]
Quantitative Information about Level 3 Fair Value Measurements
Percentage of significant unobservable input weighted-average	3.00%
Maximum [Member] | Fair Value, Inputs, Level 3 [Member] | Percentage late [Member] | Nonrecurring [Member]
Quantitative Information about Level 3 Fair Value Measurements
Percentage of significant unobservable input weighted-average	2.00%