v2.4.0.6
Fair Value, Assets Recorded at Fair Value on a Nonrecurring Basis Level 3 Valuation Techniques and Significant Unobservable Inputs (Details) (USD $)
In Millions, unless otherwise specified
3 Months Ended 12 Months Ended
Mar. 31, 2013
Dec. 31, 2012
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]    
Mortgages held for sale 42,624 42,305
Minimum [Member] | Mortgages held for sale [Member] | Discounted cash flow [Member]
   
Fair Value Inputs [Abstract]    
Discount rate 3.40% 3.40%
Loss severity 1.40% 1.30%
Default rate 0.70% 0.60%
Prepayment rate 1.00% 1.00%
Minimum [Member] | Residential Portfolio Segment [Member] | Mortgages held for sale [Member] | Discounted cash flow [Member]
   
Fair Value Inputs [Abstract]    
Discount rate 4.00% 4.10%
Loss severity 2.00% 2.00%
Default rate 1.10% 2.90%
Prepayment rate 1.00% 1.00%
Maximum [Member] | Mortgages held for sale [Member] | Discounted cash flow [Member]
   
Fair Value Inputs [Abstract]    
Discount rate 7.90% 7.50%
Loss severity 36.20% 35.30%
Default rate 14.90% 14.80%
Prepayment rate 10.60% 11.00%
Maximum [Member] | Residential Portfolio Segment [Member] | Mortgages held for sale [Member] | Discounted cash flow [Member]
   
Fair Value Inputs [Abstract]    
Discount rate 11.80% 11.90%
Loss severity 42.60% 45.00%
Default rate 6.50% 21.20%
Prepayment rate 100.00% 100.00%
Weighted Average [Member] | Mortgages held for sale [Member] | Discounted cash flow [Member]
   
Fair Value Inputs [Abstract]    
Discount rate 5.50% 5.40%
Loss severity 26.60% 26.40%
Default rate 3.50% 5.50%
Prepayment rate 5.70% 6.20%
Weighted Average [Member] | Residential Portfolio Segment [Member] | Mortgages held for sale [Member] | Discounted cash flow [Member]
   
Fair Value Inputs [Abstract]    
Discount rate 10.70% 10.90%
Loss severity 5.80% 6.00%
Default rate 3.00% 7.90%
Prepayment rate 66.30% 66.70%
Nonrecurring [Member]
   
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]    
Mortgages held for sale 3,197 2,554
Level 3 [Member] | Nonrecurring [Member]
   
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]    
Mortgages held for sale 1,042 1,045
Total insignificant level 3 assets 73 148
Total 1,115 1,193
Level 3 [Member] | Nonrecurring [Member] | Residential Portfolio Segment [Member] | Discounted cash flow [Member]
   
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]    
Mortgages held for sale 1,042 1,045