Fair Value Disclosures - Narrative (Details) (Level 3 [Member], USD $) In Billions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets and Liabilities, Fair Value Disclosure	$ 6.8	$ 7.1
Fair Value, Assets and Liabilities Fair Value as Percent of Total Assets	52.00%	56.00%
Fair Value, Assets and Liabilities, Fair Value as Percent of Total Financial Instruments Measured at Fair Value	73.00%	73.00%

Fair Value, Assets and Liabilities, Fair Value as Percent of Total Financial Instruments Measured at Fair Value

No definition available.

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Period Type:	instant