Fair Value Disclosures - Narrative (Details) - Level 3 [Member] - USD ($) $ in Billions	Jun. 30, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets and Liabilities, Fair Value Disclosure	$ 6.0	$ 5.5
Fair Value, Assets and Liabilities Fair Value as Percent of Total Assets	39.00%	38.00%
Fair Value, Assets and Liabilities, Fair Value as Percent of Total Financial Instruments Measured at Fair Value	76.00%	73.00%

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

Name:	us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration