Fair Value (Details 9) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage loans held-for-sale	$ 49	$ 10,716
Goodwill impairment	1,868	0	0
Non Recurring [Member] | Real Estate Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value Prior to Measurement	16	0	33
Gain (Losses)	(6)	0	(25)
Non Recurring [Member] | Real Estate Funds [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value After Measurement	10	0	8
Non Recurring [Member] | Customer Relationships [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value Prior to Measurement	109	0	0
Gain (Losses)	(77)	0	0
Non Recurring [Member] | Customer Relationships [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value After Measurement	32	0	0
Non Recurring [Member] | Held-for-investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value Prior to Measurement	439	166	179
Gain (Losses)	(11)	(15)	(15)
Non Recurring [Member] | Held-for-investments [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value After Measurement	428	151	164
Non Recurring [Member] | Held-for-sale [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value Prior to Measurement	350	61	35
Gain (Losses)	(31)	(3)	(2)
Non Recurring [Member] | Held-for-sale [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage loans held-for-sale	319	58	33
Non Recurring [Member] | Other limited partnership interests [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value Prior to Measurement	87	18	35
Gain (Losses)	(33)	(5)	(12)
Non Recurring [Member] | Other limited partnership interests [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value After Measurement	54	13	23
Non Recurring [Member] | Goodwill [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value Prior to Measurement	1,868	65	0
Goodwill impairment	(1,868)	(65)	0
Non Recurring [Member] | Goodwill [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value After Measurement	$ 0	$ 0	$ 0