Variable Interest Entities (Fair Value Unobservable Inputs) (Details 3) - Consolidated investment entities [Member] $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2015 USD ($) $ / ft²	Dec. 31, 2014 USD ($) $ / ft²
Summary of the significant unobservable inputs
Debt	$ 6,976	$ 6,030
Other assets [Member] | Minimum [Member] | Discounted cash flow/market comparables [Member]
Summary of the significant unobservable inputs
Equivalent yield	2.80%	4.40%
Expected rental value (per square foot) | $ / ft²	5	3
Other assets [Member] | Maximum [Member] | Discounted cash flow/market comparables [Member]
Summary of the significant unobservable inputs
Equivalent yield	11.60%	12.00%
Expected rental value (per square foot) | $ / ft²	173	94
Other assets [Member] | Weighted average [Member] | Discounted cash flow/market comparables [Member]
Summary of the significant unobservable inputs
Equivalent yield	5.90%	6.50%
Expected rental value (per square foot) | $ / ft²	50	34
Debt [Member] | Discounted cash flow [Member]
Summary of the significant unobservable inputs
Annual default rate	2.50%	2.50%
Debt [Member] | Minimum [Member] | Discounted cash flow [Member]
Summary of the significant unobservable inputs
Discount rate	1.70%	1.20%
Constant prepayment rate	5.00%	5.00%
Loss recovery	36.40%	36.40%
Debt [Member] | Maximum [Member] | Discounted cash flow [Member]
Summary of the significant unobservable inputs
Discount rate	9.00%	8.30%
Constant prepayment rate	10.00%	10.00%
Loss recovery	63.60%	63.60%
Debt [Member] | Weighted average [Member] | Discounted cash flow [Member]
Summary of the significant unobservable inputs
Discount rate	2.90%	2.40%
Constant prepayment rate	9.80%	9.80%
Loss recovery	62.70%	62.70%
Level 3 [Member] | Recurring basis [Member]
Summary of the significant unobservable inputs
Other assets	$ 2,124	$ 1,935
Debt	$ 6,976	$ 6,030