Consolidated Investment Entities (Details 2) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Summary of changes in Level 3 assets held by consolidated investment entities
Transfers (out of) Level 3	$ (3,900)
Corporate debt securities | Consolidated Investment Entities:
Summary of changes in Level 3 assets held by consolidated investment entities
Balance, at the beginning of the period	6
Cumulative effect of accounting change		15
Purchases, Net-Assets	3
Sales, Net-Assets	(2)
Settlements, Net-Assets	(1)
Purchases, Sales, Issues and Settlements, Net		(9)
Transfers (out of) Level 3	(2)
Balance, at the end of the period	4	6
Common Shares | Consolidated Investment Entities:
Summary of changes in Level 3 assets held by consolidated investment entities
Balance, at the beginning of the period	11
Total Gains (Losses) Included in Net Income-Assets	6	4
Sales, Net-Assets	(4)
Transfers into Level 3	29	7
Transfers (out of) Level 3	(29)
Balance, at the end of the period	13	11
Changes in unrealized gains/ (losses) included in income relating to assets held	3	4
Other structured investments | Consolidated Investment Entities:
Summary of changes in Level 3 assets held by consolidated investment entities
Balance, at the beginning of the period	22
Cumulative effect of accounting change		5
Total Gains (Losses) Included in Net Income-Assets	(1)	1
Purchases, Net-Assets	3
Purchases, Sales, Issues and Settlements, Net		12
Transfers into Level 3		4
Transfers (out of) Level 3	(24)
Balance, at the end of the period		22
Changes in unrealized gains/ (losses) included in income relating to assets held		1
Syndicated loans | Consolidated Investment Entities:
Summary of changes in Level 3 assets held by consolidated investment entities
Total Gains (Losses) Included in Net Income-Assets	(12)
Purchases, Net-Assets	208
Sales, Net-Assets	(40)
Settlements, Net-Assets	(137)
Transfers into Level 3	615
Transfers (out of) Level 3	(292)
Balance, at the end of the period	342
Changes in unrealized gains/ (losses) included in income relating to assets held	(5)
Other assets | Consolidated Investment Entities:
Summary of changes in Level 3 assets held by consolidated investment entities
Balance, at the beginning of the period	887	831
Total Gains (Losses) Included in Net Income-Assets	13	67
Total Gains (Losses) Included in Net Income-Assets and included in Other Revenues in the Consolidated Statement of Operations		69
Total Gains (Losses) Included in Net Income-Assets and included in Net Investment Income in the Consolidated Statement of Operations		2
Total Gains (Losses) Included in Other Comprehensive Income-Assets	(10)	(35)
Purchases, Net-Assets	299
Sales, Net-Assets	(81)
Settlements, Net-Assets	1
Purchases, Sales, Issues and Settlements, Net		24
Transfers into Level 3	7
Transfers (out of) Level 3	(8)
Balance, at the end of the period	1,108	887
Changes in unrealized gains/ (losses) included in income relating to assets held	19	40
Changes in unrealized gains/ (losses) included in income relating to assets held-other revenue	20	42
Changes in unrealized gains/ (losses) included in income relating to assets held-investment income	(1)	(2)
Debt | Consolidated Investment Entities:
Summary of changes in Level 3 assets held by consolidated investment entities
Balance, at the beginning of the period	(5,171)
Cumulative effect of accounting change		(4,962)
Total Gains (Losses) Included in Net Income-Liabilities	(89)	(339)
Issues, Net-Liabilities	(27)
Settlements, Net-Liabilities	575
Purchases, Sales, Issues and Settlements, Net-Liabilities		130
Balance, at the end of the period	(4,712)	(5,171)
Changes in unrealized gains/ (losses) included in income relating to liabilities held	$ (64)	$ (339)